First-world Solution Needed for Third-world Plumbing

[Foreigner]

As background: because of an intermittent water supply, most of the houses here have a large (5-12000 liter) cistern that water from the street flows into. Water is then pumped into a head tank on top of the house and gravity feeds into the house plumbing. Many also adapt the same pump to pressurize the house.

We just moved into a new place that has a different setup. We live in a zone that has water from the street 24/7 (very unusual). The problem is that the pressure is only good between about 7pm and 10am. So the house has a 1000 liter cistern and a pump with a pressure tank that pressurizes the house:

The water flowing into the tank is regulated by a float valve.

The problem is that when the pump is on it runs almost continually, as it makes a loop of pulling water out of the tank and pushing it back into the tank. So unless we're doing laundry or taking a shower, we leave the pump off and just deal with it.

I'd like to make it work better, so I can leave the pump on all day, but I don't have the liberty to do much with the system, as we're renting.

I was thinking about adding a secondary tank that would gravity feed into the primary tank. This would give us a larger supply of water to work with as well as keep the lower tank full so the pump isn't continually running. I would keep the inlet closed on the upper tank during the day probably, then shut down the pump and open the valve at night, to let it fill.

The big hairy question is: am I missing something really stupidly simple that I could change in the setup of the pressure switch on/off or the float? Is there a simpler way to do this?

 

[Foreigner]

Obviously the best solution would be to make it like the rest of the houses here, where street-tank and tank-house are two separate systems. I need to do some more poking around to see if that would be feasible.

 

[bkfj40]

it seems to me that your system needs to be replumbed. The street water should go into the cistern tank. All of the house water needs to come out of the cistern tank and then come out of the pump and pressure tank. That will make it quite a bit more consistent.

 

[Tapage]

plenty of our houses have some sort of tank to deal with the same water issue down here .. ( upper considering your position in the globe )

They just fill the tank with street pressure ( usually it's pretty good from 11 pm to 4 or 5 AM and there is " tha " pump that build pressure for home ..

So how I see .. or either 2 pumps ( one to feed the tank and other to pull water from tank ) and check valve .. so water out of the tank will no return to it .. and instead it's going to the house ..

 

[KLF]

Ya, I would focus more on why the pump isn't shutting off in the first place. Seems like you're trying to over-complicate the system.

 

[Foreigner]

it seems to me that your system needs to be replumbed. The street water should go into the cistern tank. All of the house water needs to come out of the cistern tank and then come out of the pump and pressure tank. That will make it quite a bit more consistent.

That is how most other houses here are set up, and IMO the best solution. The problem is that AFAIK I'd have to dig up a good portion of the front yard to find and separate the house from the street, then replumb it over almost 150 feet of concrete patio. Because I'm renting and plan to be here less than a year, I have no interest in putting that much money and effort into it.

Ya, I would focus more on why the pump isn't shutting off in the first place. Seems like you're trying to over-complicate the system.

The pump doesn't shut off because every time someone opens a tap, it pulls water out of the tank, which lowers the water level, which in turn opens the float valve. This lowers the system pressure and the pump stays on, pulling water out of the tank and pushing it back into it. Because of the setup and low street pressure, the tank doesn't fill while the pump's on.

Here's a more realistic visual:

For now, I'm leaving the pump on and closing the valve to the tank inlet during the day, then letting the tank fill at night. That works fine until we use up all our water.

Part of the reason for my thinking on the secondary tank is that this place was obviously plumbed the "right" way (probably off a well) at some point and the old head tank still exists:

I have no idea what condition it's in, but it still has some water in it, and it wouldn't be hard to modify the plumbing to make it work as shown above. I could even set it up (I think) to give pressure to the house at times like this morning when the power was out for over 4 hours and we had no running water. I don't understand why someone would disable the head tank in this country.

 

[Toyo FJ40]

I would just put a shallow well jet pump system in that pulls from the tank and stores the water in a bladder tank. The tee that ties the pressure water back to the tank inlet is the problem. as soon as the water level drops and the float opens to fill the tank your pressureized water dumps to the holding tank.

You need to eliminate the line from the pressure system that tees back into the tank supply line or at least put in a valve that can be shut.

a shallow well system looks like this, and you could run the water supply from the street through a spring check valve into the shallow well pump inlet and not need the cistern at all.

 

[Toyo FJ40]

After looking at your drawings it looks like the water runs through your house and then to the cistern.

It should run to the cistern and then through pump into the house.


Like this.

 

[Foreigner]

Yeah, we covered that. Nothing I can do to change it.

At this point, I don't have a way to split the system and make it right without a lot of time and expense and possibly really ticking off the landlord. I'm looking for solutions that I can add/change at the tank/pump. So far, no one here or anywhere else has bested my secondary tank idea, so I will probably move that direction. While it doesn't fix the problem, it at least gives me greater storage volume so I don't feel bad turning off the supply during the day to run the pump properly.

 

[Toyo FJ40]

When I first read your post I could only see your first 2 posts. Didn't mean repeat what others said.

If you could change the cistern float to not turn on till the tank was allmost empty but still let it refill to the top you would get longer runs on your pump. The only way I know how to do that would be with a float switch and a solenoid valve.