[TaylorAlexander]

Yeah my dad has an RO system at their house but it goes to a special tap next to the main one that is used only for drinking water, due to the waste associated. Maybe it isn’t needed for hand washing, showers, etc as long as there are good standards at the water distribution facility.

[datascienced]

Thats how I use it. In theory the waste could be used for irrigation or mixed into shower water but that requires more plumbing to deal with an external cost (in areas where water is limited).

[mattmaroon]

Well, if you live somewhere with a municipal water supply, the water just gets recycled anyway. I suppose if you’re on septic it’s still going right back into the ground it came from.

Drinking water is probably such a small percent of overall water use that wasting even a multiple of it doesn’t amount to much anyway.

So filter away! I’ll worry about my r/o waste when people stop diverting rivers to grow almonds in the desert and not a second before.

[rtkwe]

A big issue is returning it to the ground doesn't mean it reenters the aquafer you might be drawing from if you're on a well system. It happens all over the place and especially in California, the aquafers aren't replenished well by ground water (and the extreme pumping causes the aquafer to compress permanently losing water capacity).

[mattmaroon]

But again that’s entirely because of agricultural and industrial use. There’s plenty of water for homes, there’s not plenty of water for homes and mass farming in a desert.

This is the exact line of thought the people who use the water want to encourage. They want you to worry about your water use so you don’t worry about theirs.

[TaylorAlexander]

I think the point is that we should not as a general rule recommend people do RO for their entire house. Toilets, showers, and washing machines don’t need RO water and if a lot of people did a whole home RO system we would start to see waste add up.

[ridgeguy]

We live in a water supply area with water one order of magnitude harder than anywhere else in our county.

I'm putting an RO unit in our kitchen to serve drinking and dishwasher needs. Our dishwasher needs descaling after a couple of months of normal use. Other uses (shower, toilets) aren't impacted by our super-hard water, so no RO for the whole house, mainly because of the water waste you note.

[mattmaroon]

Oh. Sure. That will always be so cumbersome we don't have to worry about it. That would be a huge RO system. They don't have a lot of throughput so you'd need a big storage tank or a very large set of filters and a pump I'd think. I'm not at all concerned whole home RO will every be common.

[nicolas_t]

Only places I’ve seen it are places like China where people just don’t trust the water at all.

[mattmaroon]

A friend of mine in Brazil had a whole home filtration system (not RO) that even had a UV sterilizer at the end!