What options do I have for filtering tank water?
When it comes to filtering tank water there are quite a number of options available, however they fall into two main categories; Point of Entry and Point of Use water filtration. Point of entry involves installing larger filters on the entry to the house thereby filtering all the water flowing into the house or through the house to external taps.
These filters need to filter tens of thousands of litres and are therefore larger with a higher capacity. They also tend to be coarser and not filter as fine (approximately 10-20 micron) to try and limit pressure reduction throughout the house. The Point of Entry Systems are generally not designed to treat the water to the same quality as Point of Use Systems although it is now more common to install ultra-violet (UV) systems along with the standard filtration to kill viruses, bacteria and other living microscopic organisms.
Point of Use Water Filters are designed to filter the water at one location where it is being used such as the kitchen sink. Water Filters and in some cases an Ultra Violet System are installed under the sink with a separate tap on the sink to dispense the water.
The filters are usually lower capacity and filter down to 0.3 to 1.0 microns. Bacterial cysts such as cryptosporidium and Guardia are generally removed along with heavy metals, chemicals, tastes, odour and sediment. These Point of Use systems are therefore smaller in size, lower in cost, easier to install and produce higher quality water. Once you have decided on the type of system you require, the next step is to decide the water quality you wish to have.
Does low water pressure affect the quality of Reverse Osmosis water?
The performance & efficiency of a Reverse Osmosis (RO) system depends upon the membrane type, flow control, feed water quality (contaminants & quantity, pH, turbidity, total dissolved solids; TDS), pressure & temperature.
RO systems require a reasonably high pressure in order to function properly. Most domestic RO systems require 400kPa (60 psi) to operate efficiently and maintain performance. A minimum operating pressure of 350kPa is recommended however the units will operate down to 240kPa although this will affect the quality of water produced. If the water pressure is too low the RO will not be able to overcome osmotic pressure (the bonding between water molecules and the dissolved impurities). The higher the contaminant or TDS level, the higher the osmotic pressure. If the water pressure is too low the treated water production will be less efficient and the contaminant rejection rates much lower resulting in poor quality treated water.
A boost pump can be added to an RO system to increase the pressure and improve the quality and quantity of water produced.
Bench top RO systems are able to operate at lower pressures than under bench systems due to the fact that they do not have to work against back pressure created in the storage tank as it fills with water and compresses the air in the tank.
What is Water Hardness?
This is generally the level of calcium and magnesium ions present in the water although other cations such as strontium, iron, manganese and barium can also contribute. Hard water requires more soap than soft water to obtain a lather or soapy bubbles. It can also cause scale to form on hot water appliances, air conditioners, etc.
While some degree of hardness is present in just about all water supplies, many supplies using bore water have very high hardness levels requiring installation of a water softener or water conditioner.
Water softeners remove the calcium and magnesium ions and exchange them with sodium ions or salt. Adding salt to the water supply can in many cases be undesirable along with the water volume and residual salt that is back flushed down the drain or out into the ground every time the water softener regenerates/ cleans. This regeneration maybe required every 3-7 days.
Water conditioners on the other hand do not remove the calcium or magnesium ions they merely change the polarity or change of the ions so they do not attract each other, staying in solution rather than coating/ scaling up equipment.
What is Butterfly valve?
This is a type of isolating valve containing a circular disc inside a pipe. It is normally used in large diameter pipes and often geared to make it easier to open and close.
What is the Water Quality Monitoring System?
This can be added as an option to the Reverse Osmosis system to indicate when the membrane or drainage line has blocked or failed so the membrane can be replaced and the high water quality maintained. Without this you are unable to tell when the membrane has failed or the unit is not operating correctly unless you test the water coming from the membrane with a TDS meter. A handheld TDS meter will test it at that point in time although you will need to disconnect tubing to get a reading from the membrane outlet rather than from the system as this will be after another carbon filter, pH balancing filter, re-mineraliser or Pi filter.
The water quality monitoring system displays the quality at the push of a button and monitors the membrane output 24 hours 7 days a week from day 1. It will also alarm you when the quality goes out of specification giving you peace of mind that you are always drinking purified water.
The ASRO4R system also has the option of a flow meter as the resin filter only treats a certain volume of water before it needs to be changed. This meter indicates the remaining volume left with filter and alarms when the volume of water has been treated. The filter can then be changed and the flow meter reset.
What is the difference between the Big White and Big Blue Whole of house filters?
The units size wise are essentially exactly the same, they have the same pressure rating and the cartridges fit both units. The Big White housings are much stronger though, built from a harder more dense material than the Big Blue units hence we offer a 10 year warranty with the Big White and a 3 year warranty with the Big Blue. The Big Blue are more popular due to price. If kept out of the weather and used in rural applications the Big Blue units should last as long as the Big White however we would recommend Big White units for town water or higher pressure applications.
Do Reverse Osmosis systems remove essential minerals from drinking water?
A common misconception is that drinking water is an important source of essential minerals for the human body. While many minerals such as calcium, magnesium and sodium can be obtained from drinking water, research has shown that mineral uptake from tap water is very low. An adult can generally fulfil between 5-20% of their recommended daily intake of selected essential minerals by drinking tap water
This is provided they drink 2 litres of tap water per day and that the tap water has a relatively high mineral content. Most cities in Australia have low mineral content, partially due to the water source and the water treatment process; making it unlikely to even achieve these levels. Bear in mind there are only a select few minerals contained in tap water, while a great many are required, and essential for the basic functions of the human body to complete.
The main source for these essential minerals is from the food we eat, not from the water we drink. A balanced diet is the best method to providing all of the minerals our bodies require.
Why do Reverse Osmosis systems have wastewater?
Part of the water that flows into a reverse osmosis (RO) system flows through the membrane and comes out as treated water. The rest is used to wash away the rejected contaminants down the drain as waste.
If not properly designed, RO systems can use large quantities of water to produce little treated water or use small quantities of water and produce low quality treated water while shortening the membrane life. Most domestic RO systems are designed for a 20-30% recovery up to 50% recovery, i.e. 2-5 litres of water produced for every 10 litres of water used. This can also be expressed as a ratio of 1:4 down to 1:1. Higher recovery rates can be obtained but doing so will shorten the membrane life.
RO membranes are easily fouled if contaminants or concentrated impurities are not washed away quickly enough. The higher the contaminant or TDS level the lower the recovery rate of treated water or the more wastewater required.
Can Water Filters Remove Fluoride?
Fluoride is injected into drinking water supplies at various locations around Australia in the form of sodium silicofluoride and sodium hexafluorosilicic. As per drinking water standards this is put into the water at up to 1.5 ppm (parts per million) although the average is 1.0 ppm with possible short (a few minutes or hours) spikes over this due to equipment malfunction or human error. These short term spikes will have little effect on the capacity of fluoride removal filters.
Standard carbon filters of any type are unable to remove fluoride without the addition of special media and even when this media added, they will only remove up to 40%. To remove higher percentages requires reverse osmosis, distillation, resin, alumina or bone char.
Reverse osmosis (ie. Aqua Safe ASRO4) removes approximately 96% and requires resin post cartridges to achieve >99.99% reduction. Distillation removes a higher than 96% but is a batch process and is not considered user friendly and therefore not very popular anymore.
Alumina based systems (ie. Aqua Safe AS280) remove approximately 93% of fluoride but are not suitable for use in bench top systems or incorrectly designed under bench systems as very small trace amounts can under some circumstances leach into the water requiring removal with an additional specialised filter
Bone Char made from animal bones has been used for industrial water treatment for many years although the vast majority is not approved for drinking water treatment. Drinking water certified NSF61 granular bone char is available however, contact time with the media is very important for removal making cartridge design critical for performance. Removal rates tend to vary considerably and multiple (4 cartridges/stages) filters will be required to remove approximately 95%.
Reverse Osmosis is the recommended system for fluoride reduction/removal followed by correctly designed alumina and bone char systems. For reduction levels above 99%, we suggest specialised resin deioniser cartridges installed after a reverse osmosis or alumina system. This type of system may then also include a pH balancing and re-mineraliser cartridge to increase the water pH and add minerals back resulting in a 6 stage water filtration system.
What are the water pressure gauges for?
A water pressure gauge is installed on each Reverse Osmosis unit to confirm the unit is operating and running correctly with the required minimum pressure. They will also help determine if the sediment and carbon pre-filters are blocked and need replacement. A second pressure gauge can be fitted to the under bench units to let you know when the pre-filters are blocked while a third gauge can be added to show the storage tank pressure as this will need to be adjusted after a few years.
What is Alkalinity?
This is the sum of all alkaline chemicals in the water. A measurement of all carbonates, bicarbonates, hydroxides and other alkaline substances. It is closely related to pH and known as the buffering capacity of the water. A low alkalinity can cause the pH of the water to fluctuate widely and rapidly with small additions of acid or alkaline chemicals.
Can you loose weight drinking water?
Water is known to increase feeling of fullness. Drinking water before meals can also reduce a person’s food intake resulting in weight loss.
Weight loss can also be increased by substituting sugar-sweetened drinks for water. There is no doubt that sugar-sweetened drinks have higher calories and are a major cause of weight gain. Replacing soft drinks and fruit juices with water goes a long way in helping loose weight. Research now shows that for every serve of soft drink a day that was replaced by water, fewer kilograms were gained over the following weeks, months and years.
Is there a water bottle that filters Fluoride?
Fluoride is a very difficult chemical to remove from water and doing this in a water bottle is even more difficult due to the small amount of filter media contained in the filter. Apart from reverse osmosis or ultra-filtration membranes, resin media is generally used in water bottles and jug filters. This will remove some fluoride along with other chemicals in the water but only for a small quantity of water due to the small quantity of resin. If the filter only contains carbon then the fluoride removal will be very low probably less than 1%.
Can I remove sodium fluoride from my showers and my tap water?
Fluoride or sodium Fluoride cannot be removed by a shower filter. This can only be done by removing it from the cold water supply to the house or the cold water supply to the shower and hot water system. To remove fluoride from the tap water can be done by a whole of house filtration system or on an individual tap by tap basis.
What is the difference between a water softener and a water filter?
A water softener is designed to remove water hardness (calcium and magnesium irons) from the water supply. However it removes little else from the water as opposed to a water filter that is designed to remove sediment and other chemicals from the water but does little in removing the hardness from the water. In most applications one or the other is required, however in some instances both maybe required.
I have some kind of fumes coming from the shower drain that seems like ammonia, what can I do?
These fumes or smell could well be ammonia. A large number of town water supplies are now treated with chloramines instead of chlorine. Chloramines contain ammonia that can release as a gas when added to hot water as happens in a shower and drain.
Can you get NSF Certified sediment filters?
Nearly all water filters can be NSF certified under one or more of the NSF standards. While carbon filters are the most common of water filters to be certified, sediment filters can also be certified under standard 42 for particulate reduction. This certification covers material safety, structural integrity and contaminant reduction performance claims.
How do Carbon Filters work?
Carbon water filters are generally made from either charcoal or coconut carbon. While coconut carbon is considered the best or healthiest for drinking water treatment, charcoal is still used by some manufacturers as a more economic alternative.
The carbon is either broken up and graded into a granular form or ground into a powder and processed into a carbon block filter. Hollow carbon technology is now the latest advancement in carbon filtration providing 10 times the surface area of standard granular carbon with considerably higher flow rates and substantially higher filter capacity. Hollow carbon is derived from granular form.
The general term all of these types of carbon is activated carbon.
How Does Carbon Work
Carbon filters remove or reduce water contaminants by physically trapping them or by absorption. Each piece of carbon is generally activated with a positive charge and is designed to attract negatively charged water contaminants absorbing them as they pass over the carbon surface area. The larger the surface area of the carbon and the slower the water moves past the carbon or through the filter, the higher the contaminant removal.
Carbon coated filters have very low absorption. Higher absorption rates are achieved by carbon block filters followed by granular filters and hollow carbon.
Carbon filters are very effective at removing chlorine, herbicides, pesticides and other volatile organic compounds (VOC’s) from water but are not very effective at removing minerals, salts and dissolved inorganic compounds such as aluminum, copper, fluoride, iron, lead, silver, etc.
While carbon filters remove contaminants they also remove chlorine and other sanitisers that kill and prevent bacteria growth within the cartridge. Therefore after a period of time bacteria will start to grow with carbon cartridges. For this reason manufacturers put a usable lifespan on their cartridges much the same as a use by date on food. This is usually 6 or 12 months; after this time the cartridge should be removed from the system and disposed of even if the system has only been used for a few days during the year.
Some cartridge filters do however use secondary media such as silver or KDF-55 to prevent bacteria growth within the filter. This media cannot really be said to kill bacteria but more inhibit its growth, providing an unpleasant environment for it to grow.
Why have a Pre-Filter?
Pre-filters are usually supplied with twin-filtration systems and are designed to remove sediment and other suspended materials prior to the carbon filter. This prevents the more expensive carbon filter from blocking allowing it to remove more difficult contaminants. The pre-filter is designed to protect the carbon filter.
There are a number of sediment type filters available including string wound, polyspun, pleated and ceramic. Although we can supply all of these types we stock the higher quality polyspun, pleated and ceramic types for both hot and cold water applications.
Sediment cartridges are used in twin filtration systems to protect the main carbon or media filter from blocking prematurely or becoming fouled with suspended contaminants such as dirt, rust, sand and grit. This is particularly important where the water supply is not as clean or as highly treated.
Sediment filters are available in a number of different pore or micron sizes ranging from 0.3 to 50+ microns. They can also be absolute or nominal micron ratings. The cost generally depends upon the materials of construction and whether the filter has an absolute or nominal micron rating along with NSF certification.
Polyspun/poly fibre filters
These filters have a much smaller surface area than pleated (usually less than 10%) and are used only once. They do however have depth filtration and therefore trap more contaminants than pleated filters of the same rated micron. They also cost less. Certain types of these filters can be used for hot water applications.
These filters have pleats the same as a dress or Christmas decorations where the filter “paper” is folded many times to give the filter a large surface area up to 10 times that of a polyspun filter. This means it can trap and contain a lot more contaminants than polyspun units and has a lower pressure drop through the filter than polyspun. If pressure is critical or low a pleated filter should always be used. They are made from synthetic materials woven into a matt and can also be cleaned to some degree depending on the micron and reused a number of times.
These filters are made from porous ceramic material with the micron rating and quality depended upon the manufacturer. Various filters are available for gravity crock pots, bench top and under bench water filters. The micron rating of the filters generally varies from 0.3 to 5 micron with 1 micron the most common. Of all the manufacturers, Doulton is considered the world leader for this type of filter.
What is Ultra Violet Filtration?
Ultra violet (UV) light is a natural part of sunlight and is a particular selection of wavelengths from the light spectrum. It damages the DNA molecules in bacteria, viruses, and other micro-organisms preventing them from replicating and surviving to cause harm. UV light inactivates within seconds micro-organisms and viruses by a photo chemical reaction within their vital DNA. This natural process allows environmentally friendly and reliable water disinfection without chemical additives. The process was developed for water filtration in the fifties and sixties and has grown in use and popularity since. The technology itself dates back to the early 1900’s.
UV systems are now in use in almost every industry worldwide including Hospitals, hotels, schools, power stations, drinking water treatment, dairies, cheese factories, fish farms, food and beverage, water fountains, electronics manufacture, pharmaceutical, cosmetics etc.
Germ killing UV light can be produced by a variety of lamps or arc tubes. The best suited are medium or low pressure mercury lamps. No micro-organisms are known to be immune to UV light. It is effective against bacteria, moulds, fungal spores, viruses and yeasts.
Ultra Violet rays are invisible and form part of the electromagnetic spectrum. They range from 10-400 nm and are situated between x-rays and visible light. The main UV spectrum is however between 200 or 400 nm and is subdivided as follows:
UV-C 200-280 nm
UV-B 280-315 nm
UV-A 315-400 nm
UV-C rays are retained by the ozone layer. The UV-B and UV-A rays reach the surface of the earth causing sunburn and sun tan and are also suitable for radiation therapy.
UV systems are normally sized to achieve at least a 99.99% kill with most sized for 99.999% kill. This is calculated by the dosage of UV light measured in milliwatt seconds per square centimeter (mWs/cm²).
NSF standards for UV systems have set the minimum UV light requirements at 38 mWs/cm² for class A point of use (POU) and point of entry (POE) devices that treat visually clear water. UV systems that do not meet class A standards should be designed to achieve a minimum 30 mWs/cm² dosage to ensure satisfactory water disinfection.
UV-C rays are germicidal since micro-organisms are sensitive to this wavelength range. Maximum sensitivity occurs at 260 nm.
UV lamps need to be replaced periodically, usually every 9-12 months to ensure adequate UV dose.
UV systems can also now be used to control protozoan parasites such as cryptosporidium and Giardia with high does rates between 80-140 mWs/cm².
UV System Advantages
- No toxic by-products produced.
- Cannot overdose the treated water.
- Treatment is not sensitive to temperature and pH differences.
- Has no smell or taste residual.
- Requires very little contact time (seconds) versus minutes for chemical disinfection.
- Simple installation, small amount of space required.
- Low running and maintenance costs.
- Does not effect minerals in the water.
UV System Disadvantages
- Not suitable for water with high levels of suspended solids, turbidity, colour or soluble organic matter.
- Unit performance is affected by microbial loading and chemical characteristics such as nitrites, sulfites, iron and hardness levels.
- No disinfection residual ie no free chlorine.
Typical UV Systems Include:
- A stainless steel treatment chamber.
- An inlet and outlet.
- A quartz lens and lamp.
- An electrical connection containing transformer, a UV lamp fail alarm and other components.
Other Options may include:
- Inbuilt surge protection or voltage regulator.
- Treatment chamber made from poly for use in corrosive environments.
- Multiple UV lamps in the one chamber
- Mechanical wipers to clean the quartz lens; either manual or automatic.
- Sensors to monitor the UV intensity connected to alarms.
- Lamp shut down when no flow is registered for a period of time.
- Telemetry systems for remote monitoring.
The size of the model of UV system required depends upon 3 main factors:
- The Water quality to be treated.
- The flow rate or quantity of water to be treated.
- The features or options required or selected.
Once this information is known or determined a particular model or number of suitable models can be selected and quoted.
Although the maintenance requirement is low the units UV chamber and quartz lens do need to be inspected and cleaned every 6-12 months. The lamp should also be replaced, o-rings lubricated valves, switches and sensors checked and tested.
What are Water Softners and Conditioners?
Water softeners and conditioners are used to improve the quality of hard water or reduce the effects and damage caused by hard water.
Water hardness is created by high levels of calcium and magnesium ions in the water although other cations such as strontium, iron manganese and barium can also contribute. Hard water requires more soap than soft water to obtain a lather or soapy bubbles. It can also cause scale to form on hot water appliances, air conditioners, etc.
These units vary in size depending upon the water hardness and amount of water required. They usually consist of 1 tank filled with resin media and a reservoir filled with a brine or salt solution. As the hard water passes through the resin media the calcium and magnesium ions are attracted to the media and exchanged with sodium or salt ions. This removes the hardness from the water supply. When the softener resin can no longer attract or hold any more calcium or magnesium ions the unit is back flushed (the water flow is reversed) to remove these ions and replace them with sodium ions.
One of the major draw backs with water softeners is the addition of sodium/salt into the water supply and the amount of sodium/salt, calcium and magnesium to be disposed of during the flush cycle.
There are two main types of water conditioner; magnetic and catalytic. The catalytic units are essentially an inline catalytic water treatment system. They operate by combining the following:
- Turbulence of the water through a specially designed catalytic chamber.
- Creation of a small electrical field around the chamber casing.
The combination causes a separation of the mineral particles in the water, which changes their behaviour. Particles which were previously attracted to each other, now repel and separate into smaller individual particles. This allows the separated mineral particles and salts to flow through the system with minimal interference.
Installation is very simple. The units come with either a battery pack or 240 volt power connection depending on the availability of power at the proposed site location. The water conditioners are usually fitted into the mainline after the water meter or pump before any pipe branches or junctions so all water supplied can be treated. They can also be installed at any angle without affecting performance.
Once installed many have claimed their town water has a more natural taste and feels like spring water rather than their chlorinated supply.
Other Benefits Include...
- Improved taste of water, tea and coffee and keeps your kettle/jug clean.
- Helps keep bath tap and shower walls clean with less scrubbing.
- Water saturates and cleans better, gives whiter softer clothes with less detergent.
- Dishwashers and washing machines remain clean and scale free requiring less maintenance.
- Stops scaling in piping, removes existing scale, improves water pressure.
- Lawns and gardens require less water to stay green and healthy.
- Less water spotting on windows and buildings.
- Protects water heaters from corrosion, adding years to their life.
- Reduces salt build up and encrustation on air conditioners.
- Residential and commercial uses.
- Swimming pools.
- Motor homes and boats.
- Golf courses and irrigation systems.
With sizes ranging from 6 mm (1/4”) up to 250 mm there is a unit suitable for every application and what’s more like our range of water filters they come with a 10 year warranty and satisfaction guarantee.
What is Reverse Osmosis?
This water purification process has gained in popularity over the last 20 years since it was first used commercially in 1968. It is used extensively for purifying sea water and uses membrane (a thin film or skin through which water molecules can pass) technology.
The easiest way to explain reverse osmosis is by firstly explaining osmosis.
Osmosis is the movement of a low concentration solution through a semi permeable membrane into a high concentration solution such as sea water or contaminated water.
In reverse osmosis, the idea is to use the membrane to act like an extremely fine filter to create drinking water from contaminated water. Pressure is applied to the contaminated water, reversing the osmotic process and forcing water molecules through the membrane.
Reverse osmosis membranes don’t allow particles or molecules larger than 0.0005 microns to pass through to the other side of the membrane. Essentially only water (H20) passes through while other contaminants, bacteria, viruses, chemicals and other dissolved substances are flushed to drain.
As a size comparison against 0.0005 microns; a human hair is 100 microns, the smallest particle visible to the human eye is 50 microns, the smallest bacteria is 0.2 microns and the smallest virus is 0.002 microns.
Reverse Osmosis membranes are manufactured with different pore sizes and support structures and from different materials. Membrane pore sizes can vary from 0.0001 microns to 5 microns depending upon the type and purpose.
Sea water or Desal membranes are constructed to operate at very high pressures up to 7,000 kpa with small pores that reject in excess of 99% of salt at loading greater than 32,000 mg/l.
Brackish/Salt contaminated water membranes operate at high pressures around 1,500 kpa and have larger pores to reject in excess of 99% of salt at loadings greater than 2,000 mg/l.
Lower pressure/low energy membranes are designed to operate between 400 and 1500 kpa with more open larger pores designed to reject 99% of salt at loading around 500 mg/l for ground water and municipal supplies.
There are two main types of reverse osmosis membranes commonly used in home reverse osmosis filter systems:
- Thin Film Composite (TFC)
- Cellulose Triacetate (CTA)
TFC membranes have considerably higher rejection rates; and filter out more contaminants than CTA membranes. However they are more susceptible to degradation by chlorine and other oxidants and need to be protected from them by pre-filters.
These membranes are made by forming a thin, dense contaminant rejecting surface film on top of a porous substructure. The materials of construction and the manufacturing process for these two layers can be different and altered for the desired combination of pure water produced versus contaminants rejected. The pure water production and contaminant rejection characteristics are predominantly determined by the thin surface layer which thickness ranges from 0.01 to 0.1 micrometres.
Several types of TFC membranes have been developed including aromatic polyamide, alkyl-aryl poly urea/polyimide and polyfurane cyanurate. Polyimide membranes are highly susceptible to degradation by oxidants such as chlorine and chloramine. These must be removed to prevent damage and destruction of the membrane.
These membranes were developed along with the first reverse osmosis systems in the late 1950’s. They are composed of a thin dense surface layer (0.2 to 0.5 micrometres) and a thick porous sub-structure. Contaminant rejection is undertaken by the thin dense layer with the sub-structure providing structural support. They are relatively inexpensive to manufacture and hence are cheaper to buy than TFC membranes.
CTA membranes also have a low rejection of organic contaminants, low pH tolerance but a high tolerance to oxidants such as chlorine.
The chemical 1,4 dioxane is used to create the membrane porosity features. This chemical causes cancer with some traces of it left after manufacturer requiring considerable flushing before use.
The removal of inorganic contaminants by reverse osmosis membranes is complex and is dependent upon the interactions and mixture of irons in the feed water. Ionic contaminants are more readily rejected than neutral ones and polyvalent ions are rejected to a greater extent the monovalent ions. If the polyvalent ion is strongly hydrated, rejection is even higher.
As electrical neutrality must be preserved, ions diffuse across the membrane as a cation-anion pair. As a consequence, rejection of a particular ion depends on the rejection of its counter ion. An example of this is with sodium; sodium sulfate has a higher rejection than sodium chloride because the divalent sulfate ion is rejected to a greater extent than the monovalent chloride ion.
pH variations also affect the rejection characteristics of the membrane depending upon membrane composition and ion type. For example, fluoride rejection increases from 45% to over 90% as pH increases from 5.2 and 7.2 whereas nitrate rejection decreases slightly as pH increases from 5.2 to 7.0.
A large number of councils are now using chloramine to treat drinking water supplies instead of chlorine. This chloramine contains ammonium ions which are poorly removed by activated carbon causing dramatically reduced rejection rates and degradation of the membrane. The variability of local water conditions and sources also varies the performance of the membrane although a Total Dissolved Solids (TDS) monitor will show the current performance of the unit. Specific ion rejection performance can however only be determined by selected testing. As a general guide reverse osmosis membranes are more effective in rejecting ions or organic solubles with molecular weights greater than 200 however carbon filters before and after the membrane can greatly affect the contaminants rejected or absorbed thereby affecting the overall performance of the system. The larger the pre-carbon filter ie 12” in the Aqua Safe ASRO4 unit the greater the chloramine and contaminant removal.
While membranes are successful at removing bacteria and viruses the systems can be contaminated from the product water side colonizing the tape tubes and storage tank. Regular disinfection (every 6-12 months) is necessary to maintain the water quality. This can generally be done by the system owners at very low expense or carried out by service technicians.
What are Filtration Types and Grade Charts
Contaminants in drinking water vary in size considerably from grains of sand and grit that we can see to viruses and soluble salts that we cannot see. The contaminant or particle size determines the type of filtration required or able to remove it. For instance 1 micron filters are able to remove or stop particles greater than 1 micron such as sand, silt, algae and a large portion of bacteria.
Micro filtration or finer is required to remove particles greater than 1 micron along with some viruses and all bacteria. For greater contaminant removal, finer filtration such as Nano filters would be needed remove all of the previous contaminants plus some dissolved organics and salts. Where the maximum contaminant removal is required, Reverse osmosis would be used as this is the highest quality of filtration available. Micro, Nano and Reverse osmosis filtration all use membranes to achieve the required level of contaminant removal or reduction.
The micron rating in the chart below indicates the absolute micron rating of the filter required to remove the contaminants not the nominal rating. For further information on this please refer to the glossary of terms.
What is Absolute Micron rating?
This is used to accurately define the grade or level of filtration delivered. An absolute rating means 100% of particles larger than the filter rating (usually in microns) will be removed or entrapped on or within the filter medium i.e. 1 micron absolute will remove or entrap all particles greater than 1 micron as opposed to 1 micron nominal which may still let particles greater than 1 micron through.
What is Activated Carbon?
This is a filter material made from coal or coconut shell carbon that has been processed causing the carbon to pit and change shape much like popcorn. This gives it an enormous surface area to absorb chemicals and odours from water and air. It is black in colour and comes in powder, granulated or extruded block form.
What is Algae?
These are simple tiny plants or seaweed that grow and multiply if nutrients are present and chlorine or sanitizer levels are low. Most algae are invisible except in millions. In sunlight they convert carbon dioxide into oxygen by photosynthesis. They are larger than bacteria and viruses but generally smaller than 5 microns and vary in colour from green to blue, brown and red. They can be seen inside water filter housings and on water filter cartridges, often giving a slimy feel.
What is Alum?
Alum or Aluminium Sulphate is a flocculant product used in water treatment to coagulate (bind together) colloidal very fine dirt particles and other organic materials so they fall to the bottom of a tank where they can be removed. This process then leaves the water clear. Alum is also used to remove phosphorus from water. Alum used to be used extensively to treat town water supplies. However it is being phased out due to the carryover of aluminium into the water supply. Other more synthetic chemicals are now generally used.
What is Ambient Temperature?
This is the current or average air temperature in the room/location or environment. This is usually 18°C to 28°C.
What is Ammonia?
This is a colourless gas with a sharp offensive odour. It can be manmade or produced naturally and dissolves easily in water. It is made up of 1 nitrogen and 3 hydrogen atoms and is very alkaline in water based solutions. It is found in many household cleaners and chloramines; now used extensively in town water treatment in Australia and throughout the world. It is irritating to the skin, eyes, nose, throat and lungs. Levels in drinking water should not exceed 0.5 mg/L.
What is an Anode?
An electrode, rod or pole through which a low voltage electric current flows. This low voltage causes a process called electrolysis whereby salts in the water collect on the electrode or the electrode erodes by oxidation.
What is Anthracite?
This is a form or type of activated carbon. Anthracite is a hard, compact variety of mineral coal that is graded to size and quality and used in commercial water filters due to its very high carbon content and low impurities. High grade and ultra high grade anthracite are generally only used in water filtration.
What is Arsenic?
A naturally occurring element that forms a number of poisonous compounds. Organic arsenic is less harmful than inorganic. Inorganic arsenic compounds are mainly used to preserve wood, insecticides, pesticides and weed killers. Pentavalent arsenic is generally the most common form found in surface waters while the trivalent form is found mainly in ground waters and deep lake sediments. The concentration of arsenic in drinking water should not exceed 0.007 mg/L.
What is Ballast?
These are an electronic device that regulate the flow of current through a Ultra Violet (UV) lamp.
What are Ball valves?
These are a type of isolating valve containing a circular ball with a hole through it. They are turned 90° or ¼ turn to open or close.
Does the re-mineraliser cartridge add in natural minerals or artificial?
This is an additional cartridge filled with calcium and mineral rocks that is installed either after the last carbon filter or before the last carbon filter and adds in natural minerals mainly calcium to raise the water pH to between 8-9. Normal town water is around pH 7.0 as opposed to the water coming from the RO system at between 6.5 and 6.8 depending upon filter configuration.
What is Ion Exchange Resin made from?
Resin media are generally small beads, approximately 1mm in diameter made from an organic polymer. They are yellowish or tan in colour and porous creating a large surface area.
Most commercial resins are made from polystyrene sulfonate. They do not dissolve in water, not affected by hot water and are widely used to create Ultra Pure water for use in the pharmaceutical/ medical and technology industries.
What is Zeolite?
Zeolite is a naturally occurring aluminosiliate mineral used in the water industry for filtration and ion exchange. It can also be synthetically produced. It is a more efficient media than sand for the filtration of water and is very effective for ion exchange, ion removal and water softening. Like standard ion exchange resin, once its capacity is reached it needs to be re-generated for water softening or cleaned in the case of heavy metals, iron and manganese removal.
What are megohms?
Megohms is a unit of measurement just like metres is a unit of measurement. 1 Megohm is equivalent to 1,000,000 Ohms and is used to measure the electrical resistance or the ability of water to conduct electricity. The more pure, water is, the greater the Megohms and the lower the ability of the water to conduct electricity. Ultrapure water does not conduct electricity.
Do Reverse Osmosis filters remove everything from the water?
The simple answer is, No they don’t. Reverse osmosis systems filter down to 0.0005 microns, however many contaminants are smaller than this or are forced through the membrane due to design constraints or poor design. Some contaminants are removed by as much as 99% while many others are removed by only 30-50%. This can be seen by looking at membrane rejection tables.
The average contaminant removal by reverse osmosis filter systems is approximately 85%. This will vary depending upon the quality and number of contaminants in the water supply and the system design.
The performance of a reverse osmosis system can be checked by using a TDS (Total Dissolved Solids) meter and should be between 7-10ppm.
To remove more contaminants an additional filtration stage is required. This involves one or more mixed bed DI resin filters that further purify the water removing 99.99% of contaminants. This Ultrapure water can be provided by the Aqua Safe ASRO4R system.
How pure (in parts per million) can your RO systems produce?
This depends upon the quality of the incoming water supply but generally sits between 2 & 7ppm with the standard RO system. The ASRO4R produces higher quality water and therefore lower TDS.
Is it safe using Wollastonite in your filter?
Wollastonite is a natural mineral and will not affect the water filter although I would imagine you will be installing this after the filter unit.
To make bore water potable what cartridges do you recommend?
Bore water can have a great many contaminants in it, from high hardness, salt, iron, heavy metals, Arsenic and bacteria to name a few. Without a water test we are unable to recommend any cartridges. If the water supply is of unknown quality it may be best to use reverse osmosis filtration as these systems provide the highest degree of filtration or seek an alternative higher quality supply.
I would like some information about the re mineralising cartridge .What kind of cartridge is it ? How doest it work ? How and what minerals are added into water? Can I have 6 stage filter- the resin to remove 99, 9 % the fluoride? How much does it cost
The remineralising cartridge is an inline 275mm long that is usually installed after the reverse osmosis filter process to raise the pH of the water. It can be installed as a final stage or installed before the last carbon filter to reduce the effects of the cartridge.
The cartridge contains a number of ceramic balls and mineral rocks that essentially add calcium into the water raising the pH to between 8-9.5 depending upon the incoming water. The cartridge also reduces the Oxygen Reduction Potential (ORP) of the water to between -25 to -180mv to assist the bodies metabolic functions.
A remineraliser can be added as 5th or 6th stage to a 4 stage reverse osmosis system and can be installed after a resin cartridge although it is already included as standard os the ASRO4R unit.