The community water system is old. The main system (well, tank and pumps) is only about 20 years old, but the pipes in the groud that connect all the homes are over 50 years old. Even when no one is using any water, the system leaks a couple gallons a minute.
Every year, sometimes several times a year, there's a bigger leak somewhere in the system requing the pressure pumps be turned off until the leak can be found, isolated, and fixed. Last year it was a leak on a cabin in Division 1, and later sink in a cabin in Division 2. This year it was a brand new connection to a cabin under construction. Whatever the reason, when the pressure pumps are turned off, water pressure to KnArrow Haus drops to a trickle. Not very useful if you want to take a shower, run the dishwasher, or flush a toilet.
After a several-week pressure outage last year, one of the long-time neighbors just down the hill showed me the backup tank and system he designed and installed many years ago to the combat the problem. I took videos and pictures of his system, then spent a few weeks thinking about and designing my system. Putting the system in was my Summer 2022 cabin project.
Design for KnArrow Haus backup tank and pressure pump.
I used this to build my shopping list.
The system incorporates a water tank and a pressure pump to supply water if the system pressure is low or off. The tank automatically fills, allowing the backup tank to do what I call "a lazy fill" when the pressure is low. A auxiliary water pump provides pressures the system on-demand, but only when the main system pressure is low. When the main system pressure is high, the pump never turns on.
I can drain the whole house's system in to the tank if needed. And we also get the added benefit that we can close the main shutoff to the house when we leave but still run the dishwasher before we walk out the door. If the house were to spring a leak or burst a pipe while we're gone, only the water in the tank would spill in to the house, but no more.
The water shutoff and manifold before adding the backup system
Preparing the tank shutoff
The fill valve for the tank is essentially a toilet-style float valve, only bigger. Instead of the typical half-inch flow, it is a one-inch valve designed for larger tanks so they can fill quickly.
Through-fitting with shutoff installed at top of tank
Measuring the space between the tank and washing machine
Installing the flexible connecting fittings to the pressure pump
The drain valve at the bottom of the tank connects to the pressure pump,
and it has a shutoff tee so the tank can be drained if needed
I built a small bench from scrap wood to raise the pressure pump off the floor
View to the tank drain valve. I put a hose fitting on the end
Doing a tight loop with one inch PEX isn't very easy.
This was the final connection I made to the system.
The new backup system all plumbed in a ready for service.
Of course, with every new system it seems like there's always something that fails. In my case, there were actually 2 things that failed after connecting it all up at the end of the Summer.
The first failure was one of the two sharkbite pressure valves. One had a slow drip that I could never get to fully seal. I tried disconnecting and reseating it several times, and even tried cleaning up the end of the PEX pipe. Nothing work so I simply removed it and replaced it with PEX. I cannot check the pressure of the outside water system now, but it's not a major loss.
The second failure was the through-hull fitting at the top of the tank. About a month ago, right after we turned on the main to the house, Katie told me water was dripping all over the floor. I ran downstairs and realized the connection through the top of the tank had broken.
The through-hull fitting at the top of the tank that broke.
In this picture you can see the shutoff valve on top of the tank
that I had to fish out form the bottom.
The brass fitting through the tank snapped in half. Probably because I overtightened it.
The new nylon fitting I bought required a much bigger hole in the tank
New through-hull fitting connected. System restored.
Now that everything is back and restored to working condition, I've reevaluated what else can go wrong. The one weakness in the entire design that I can think is the float valve itself could fail. If for some reason it were to fail meaning "not shut off" -- which would only happen while we are there with the main water turned on to the house -- it could cause the tank to overfill and leak water all over the basement floor. Again, this would only happen while were are there with the water turned on. There is no drain in the basement floor...
I guess you'll hear from me again on this subject if/when that happens.
