Low Pressure System / Off-Grid Ranch House

[Pablo Rodriguez]

Hi - I’m hoping for some guidance on replacement of two toilets at an off-grid property which are fed via gravity by a 500 gallon water tank.

The current set up is very inadequate as the maximum pressure to the compression valve is only ~5psi. A pressure-assist toilet is impossible given the minimum 20psi pressure needed and an interim tank + pump to increase pressure to the house is also out of the question.

Given the pressure situation, is there any toilet on the market which performs well at very low pressure?

I appreciate any insights others may share to this and can help to answer any questions regarding the set up to help with guidance.

 

[John Gayewski]

I think I would modify the fill valveand call it a day. This would take some tinkering, but to your question. Most plumbing fixtures aren't made for pressures that low.

 

[Sponsor]

 

[Reach4]

You were seriously considering a pressure assist toilet, or were you just joking?

I think the old ballcock would work with such low pressures. I think the newer towers may have some kind of pilot valve where water pressure plays a roll. My comments are based on vaguely remembering earlier posts.

 

[Pablo Rodriguez]

Thank you, guys, for the replies. I did consider a pressure-assist until I learned how far off I was from the operating pressure minimum (and I don’t have a 50 foot water tank in my backyard). Was actually sad I couldn’t replicate an airport bathroom in my little ranch house.

I’m also looking at other options like finding a toilet with a larger tank (than 1.6gpf) either at an old property in the area or south of the border. But I’ll look at replacing some components and seeing if I could get a better flush.

 

[Jadnashua]

Other than a flushometer, or pressure assisted toilet flush valve, water pressure has nothing to do with how well it flushes. Yes, on a gravity flush toilet, the height of the tank can make a slight difference and yes, some of the fill valves rely on the incoming water pressure to work properly.

Personally, I'd put in a booster pump. As long as you are not volume limited, these things don't have to be large or expensive. But, they do take power, and if electric power is the issue, I guess you're stuck.

The older ballcock shutoffs should work to shut the water off as they just rely on the buoyancy of the float as the water fills the tank to shut things off - water pressure isn't involved as the valve should open when the ball drops when the toilet is flushed.

More volume doesn't necessarily equate to a better flush...it's what you do with the water, and the amount of water can affect how well the bowl gets rinsed off, though. SOme are much better than others at this. I doubt it's legal in AZ to buy a toilet that uses more than 1.6g, and it might even be less than that. In TX, it's illegal to buy, sell, or install a toilet that uses more than that, but don't know about AZ.