Aqua Safe reverse osmosis systems are certified to NSF standard 53. NSF standard 58 is a higher standard certifying the complete Reverse Osmosis system. NSF certification is expensive to obtain and then requires ongoing testing and auditing to maintain. Hence most products with NSF certification tend to be more expensive however customers also know that they have been tested and meet a level or standard of quality. NSF standard 58 certification is however completely different to WQA Gold certified to standard 58. Products with NSF standard 58 are tested and certified by NSF International. WQA or Water Quality Association certified does not mean it meets NSF standard 58; this is more a marketing use of words to promote sale of products. It can only be tested and certified by NSF to meet the standard. There are 3 tubes coming from the bench top reverse osmosis system. One white tube connects to the tap to supply the inlet water, the second white tube is used to fill jug or container while the black tube is the drain or membrane flushing and usually runs down the drain or can be used to fill a bucket to water the garden etc.