water changes

reefkeeperZ

Member
I try to use my waste water for watering house plants and my garden, since I live in the city I pay both water and sewer on all the water I might as well use it.
 

pegasus

Well-Known Member
I have an RODI that can push out 52 gallons in about 16hrs. The biggest thing is the waste water is huge. We normally have the waste water going straight down the drain, we did a little experiment the other week, and collected the waste water while filling a barrel with RODI.
The ratio was unbelievable. for every 1 litre of good RODI water we saw approx 2.5 litres go down the drain,
I have a friend that is on a different water supply to us and his waste is about half. So I know it varies, but wow we were shocked at the shit that it must filter out. So I personally wouldn't run a tank without one.
The most deciding factor when it comes to product/waste ratio is pressure. If you have low water pressure (most households do), then the waste will typically run at a ratio of 3:1. One gallon of product water for every three gallons of waste... which means it takes 4 gallons of tap water to make 1 gallon of pure water. This is generally unacceptable, and the best way to overcome this is with a booster pump. Water pressure that's less than 50 PSI results in massive waste, although it's not quite as bad with 75 GPD RO/DI units. It's still bad, but not quite as bad as 150 GPD units. I have a 100 GPD RO/DI with a booster pump, and when I test the product/waste ratio, it's 1:1... both containers fill at exactly the same rate. The added pressure makes your RO membrane much more efficient. When I first set up my unit, I was barely getting a trickle of product water. I tested my water pressure, and it was 37 PSI. Not ideal pressure for an RO/DI unit. With the booster, I get a nice, steady stream with a (open and running) pressure of 55PSI. While a bit pricey, a booster pump is a great investment IMO.

Instead of running the waste water down the drain, save it in a plastic garbage can or tote, and use it to water your garden or flower bed(s) if you have any of those. Wash your car, or clothes, or whatever. You can use it the same as you would tap water... but don't drink it! LOL!!!
 
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