Compressed Air Well Pump and Pressurized Home Water System Bubbles- Part 2, by H.W.

Acquiring Parts

To build this pump, I wandered for about two hours through the plumbing section of one of the big box home improvement stores. I love it when the guys who work there come up to me and ask what I’m looking for. I tell them I have no idea, and then I show them the back of my envelope with still-wet scribbles, as I design my project in real-time while I’m walking through the store! They see this a lot, I think. It might be called Home Depot engineering.

I’ve noticed that the big box stores have stopped carrying many of the parts I used in my pump. I guess the market for these oddball parts is not too large. However, you should be able to find them at a plumbing supply house locally. Just take a lunch and ask if you can wander through the warehouse!

To connect the parts, I used generous amounts of PVC cement. I also ran two stainless steel sheet metal screws through the end caps into the PVC pipe with some cement in the pre-drilled holes, just to be sure it would all stay together. Heating the screws before installation makes for a permanent fit. Don’t rely just on glue to hold the weight of the pump; it could be an expensive mistake if you loose the pump or parts of it down the hole!

The check valves are the most expensive parts of this pump, costing about $20 each. They are brass. My water has a lot of lime in it, but the valves have continued to work well in spite of that. You might want to put a filtered foot valve on the bottom of the pump, if your water contains a lot of silt.

One Internet source recommended removing the springs from the check valves, but this will totally disable the pumping action, so please ignore that advice.

On the compressor side, it’s a good idea to use a filter on the air line going to the pump, as you don’t want to be drinking whatever crud is in your air tank. This made me a bit leery about using compressed air, especially since we have no idea what is going into these Chinese compressors that we buy from the discount tool stores. However, I have had no problems or funny taste in the water with the filter in line.

Water Storage

After getting the water into your home, you will need to store it. You can purchase what are called “doorway tanks” from reputable suppliers. These are poly tanks that will fit through a 30” wide doorway, which are typical of residential installations. I was able to wrangle a 250-gallon tank into an isolated basement utility room with a helper. You should expect to pay about $2 per gallon of capacity for these tanks. The tanks at the farm store typically run $3 to $4 per gallon. My 250-gallon tank cost about $500, delivered on a truck to my door. This one weighs about 100 pounds when empty.

Before installation, I used a garden hose and a new floor mop to clean out the tank in the back yard, with liberal application of bleach. This was a new tank and had not contained any other materials before purchase. Once installed, I did fill the tank and let it sit for about a month before emptying it and refilling. That took care of any plastic odor or taste.

You’ll need to locate the tank on a concrete floor, as water weighs about 8.3 pounds per gallon. My tank weighs over one ton when full!

I set the tank not directly on the concrete but on a piece of concrete backer board used as a foundation for tile projects. Many sources recommended not setting the tank directly on concrete because of absorption of chemicals through the plastic. I’m not too sure about the veracity of that advice, but I compromised by using the backer board. I sprayed the board with some bleach on the bottom side, so that if the tank wept condensation at least I would not have a mold issue. So far, the tank outside has been bone dry, and the water tastes great.

To fill the tank quickly from my regular well pump, I put a tee fitting and ball valve draining into the tank from the incoming well line with an inline cartridge filter. It takes only about 15 minutes to fill the tank initially. I also add bleach to the tank if the water will be sitting for a considerable period. I use a liquid ounce of bleach for the 250-gallon tank. The odor is detectable, but not objectionable, and the water is crystal clear.

Raising Water to Upper Levels of House

I pondered how to get the water out of the tank in the basement up to the living levels of the house. Eight point three pounds per gallon is not a wife-friendly number when carried up the basement steps! I first bought some foot operated galley pumps that you might find on a boat. These worked merely okay, but they did not seem to hold their prime. I would have had to pump for a while to be able to brush my teeth.

Next, I researched electric water pumps and found that the RV industry has a ton of options. I settled on a 12V pump that has a servo controller to provide proportional pumping action, to maintain a constant pressure. This pump was about $250 at a camping gear chain store. There are less expensive pump options with the usual pressure switch at about half that price. These pumps will run dry without damage, in case the tank empties.

With the pump in hand, I plumbed it into my house’s system. I ran a spare piece of half-inch PEX from the water tank over to the pump, which is near my well pressure tank and main cutoff valve. This had to go up and over a wall, and it turns out I needed a check valve at the tank end to prevent the supply line from draining dry with the pump off. From the output of the pump I ran the line through a manual valve and then into my main water supply pipe.

I have the two manual valves situated so I can supply the main house water line from the well and pressure tank, or from the 12-volt RV water pump. The servo controller in the RV pump is confused by the pressure tank, and the instructions say to avoid using one with that pump. When the pressure tank is on the line, the servo controller generally works, but when no water is running the RV pump sometimes turns on at a very slow speed or oscillates. Turning off the valve to my main well and pressure tank line solves that problem.

The proportional action of the RV pump means that it does not run full bore when running the water slowly. When taking a shower, the pump runs flat out and makes a bit of noise in the basement, but we cannot hear it on the first floor of the house. I run the RV pump from my 12V solar batteries through a Rigrunner fused power feed block. The pump draws about 8 amps maximum (100 watts) and uses a lot less when it’s running slowly.

It is very nice to have pressurized water running through my normal house plumbing even when the power is out. My family has not expressed any reservations. In fact, the RV pump maintains a constant 30PSI, while the regular well pump with pressure switch allows the pressure to roam over the typical wider range of 25-50PSI. I actually like the constant water pressure better.

Another of the aspects of this system I like is that all the equipment down in the hole is not electric, and so it is not susceptible to EMP. If you keep your air compressor and power source shielded, you can have water whenever you need it.


As for my costs, not including solar power, here is the breakdown:

PVC pump parts: $100
PEX tubing, 500ft: $129
Wire rope, 1/8 inch: $61
Well cap: $15
Air compressor, 20 gal: $250
Water tank, 250 gal: $500
Air valve control rig: $75
RV water pump: $250
Total: $1380

I hope my experience will help those of you with electric well pumps have some other options to get water out of the ground after the lights go off. Keep your powder dry, water wet, and be ready for constitutional reconstruction after the crash!