Water Filtration System

agesilaus wrote:

Bumpyroad wrote:
recirculating waste (dirty) water back into the feed water system would make that water dirtier and dirtier wouldn't it? what does that do for efficiency.
bumpy

I was assuming that we misunderstood what he meant to say, but you are correct, it would degrade the quality of the water in the tank.

Depends on the filter. Residential RO waste water is essentially water that isn't pushed through the system. Water at a certain PSI has to pass through a series of smaller and smaller filters , down to the bacterial micron level. So from 40-60 psi you end up with a trickle of water . That's why RO's have holding tanks and they take so long to fill. There is a relief valve for water than can't pass through so it doesn't cause back pressure on the supply line. It goes down the drain. So it's not "dirty" water, it's just the original water that didn't get passed through the system. It's like using a 5 gallon bucket to fill a 12 oz glass. What doesn't fit goes all over the floor - or in the RO's case, down the drain. It's called waste because it's wasted/rejected/never made it into the system (unless recycled). It's not waste because it's dirty. All the impurities are collected in the filter membranes themselves and stored until exhausted and then replaced. So by recycling the "waste" water in an RO system you are simply continually trying to push the same water through the system until it finally makes it. It's not any dirtier than it was to start with - it just never got polished.

I'll add another caution of RO systems in general for whole house or whole RV purpose. RO filters everything - including Chlorine and Chloramine which can kill bacteria that can live in your plumbing system and holding tanks. So while you don't want to drink them and it's good to filter them from drinking water, your whole house/whole RV should not be filtered from things that inhibit bacterial growth. RO is for drinking. But there are more pros than cons to filtering an entire house/rv.