We never had a setup like we have now when we lived in the US - but I suspect people have somewhat similar setups - particularly people who collect rain water. We have a community well - which provides water at the street perhaps half the time (very random). Because of this randomness we have storage tanks. We have a 1100 L tank on the roof which can receive water directly from the street (if the water pressure is good enough) or we can pump water up there (from our in ground tanks). So that tank on the roof feeds water to the house using gravity - although we do have a setup to increase the water pressure so we can really get a strong shower. We have a smallish in ground tank (maybe 5 meters square) which is used to principally feed the sprinkler system. We just built a new in ground tank (perhaps 18 meters square) which we plan on using to pump water to the roof if it is needed. We just added a little bit of chlorine to all three tanks (as there is nothing added to the well water at its source). We have a cheapo filter at the street to keep out dirt. And we have the same cheapo filter at the tank at the roof. We have a 5 filter RO system under the kitchen sink. We only drink water from that sink. We have a $10 gauge at the street to tell us if there is water pressure. We also have a $100 wireless water level gauge sitting in the tank on the roof which tells us if we need to pump water up. Yes, we could set the pump on automatic - but because of the way things are prioritized, we know that if the tank on the roof is full, the two in ground tanks are also filled. Our lot tilts down slightly. The two in ground tanks are lower than the house. Without the use of the pump - I can't see any chance water from those tanks ever going up hill. BUT (and this is the root of my question) I do not understand what is keeping the water on the roof from going back out to the street. For all three of our tanks the water is 'potable' (although we would never drink it directly. Is a backflow preventer used solely to keep the contamination of the drinking source OR might we need a backflow preventer to assure the water stays on the roof (since we pay for the water by the cubic meter). Sorry for rambling - Thanks for your opinion. Edit : I guess I just answered my question in my head. The water going into the tank on the roof comes in at the top - goes out at the bottom. So the water source is above the water line of the tank.

Hello all, I'm (finally) getting to the plumbing portion of my basement finishing project. This will be my first time working at all with plumbing supply. I'm adding a full bath and a wet bar (so two sinks, shower, toilet for total fixtures). The existing supply lines are all copper and I've had no leaks or other problems (aside from some banging). Conveniently the lines run behind the wall of the new bathroom before going to the kitchen, laundry, and baths on upper levels. I was initially assuming I'd just make a couple cuts to T out for the new bathroom and a second for the bar sink. I've done some light electrical soldering and am reasonably confident in my ability, though I am a bit leery if I'd have trouble fitting the cut copper to adapters when it is already rigidly in place. Since I've started researching I'm hearing that PEX is apparently the best thing ever to happen to plumbing and am leaning toward that instead. It sounds like it wouldn't be hard to cut out a small section of the hot/cold, put in a small length of pex with adapters on either end, then make additional Ts and runs for the new fixtures. However, the manifold approach seems very appealing without too much extra effort. I could cut out the entire length of copper and just leave what goes up to the upper floors... then set up a manifold with an adapter to the copper for the existing rooms/fixtures. What I do NOT intend to do is a full retrofit and replace the plumbing on the upper floors. So I feel like I have a pretty decent idea of what each approach would entail and am just looking for some opinions. What would you do if this were your house and you weren't on an extremely tight budget (but enough that you didn't want to hire a professional!). Do you think I shouldn't fix what isn't broke? Is it worth building in a manifold? Is PEX overrated and should I stick with copper to copper? Thanks for all opinions and expertise!