Automatic Pool Water Filler




Introduction: Automatic Pool Water Filler

This device will automatically add water to your pool when it gets below a specified level. It does this all for under $15. By having a device fill the pool to a specific level, you can avoid wasting water by overfilling.

Step 1: UPDATE: VERSION 2.1 Cross Section Added for Stability

After version 1.0 kept falling over in the water, I added a cross section for stability. I spray painted the PVC Black to help protect it from the sun. It also makes it look much more finished.

Step 2: Materials

You Will need
(1) Toilet Tank Fill Valve
(1) 3/4" PVC Pipe (At least 2 feet)
(3) 3/4" PVC 90 degree Elbows
(1) 3/4" slip fit to 1/2" threaded reducer
(1) 1/2" threaded coupler
(1) hose threaded to 1/2" reducer (I would recommend using a brass fitting, as it is much more durable. The rotating part tends to pop off of the PVC ones.)
(1) AquaMend Underwater Repair Epoxy Stick
(1) Teflon Tape
(1) PVC Pipe Cement
(1) 3/4" PVC 4 Way Cross Section***
(2) 3/4" PVC End Cap***
PVC Pipe cutter (or saw)
Groove lock pliers

***Please see UPDATED section for picture of 4 way pipe fitting and end caps

Step 3: Cut the Vertical Piece

Cut the vertical piece of pipe that will hold the entire assembly low over the side of your pool.

Step 4: Add Elbows to Vertical Piece

Add two of the 90 degree elbows to the vertical piece, facing opposite directions.

Step 5: Epoxy Toilet Valve Into 90 Degree Elbow

Take the AquaMend epoxy out of its tube and cut off approx. 1 inch. Knead it together until a uniform color is achieved. Mold it into a string, and tear it in half. Set one part aside, and roll the other out, using the tube as a rolling pin. Get it long enough to wrap all the way around the threads on the valve. Wrap it on the threads and insert it into the tube as far as it will go. Use the second part you set aside earlier to form a nice, graduated seal on the pipe. Smooth this out with your fingers. Allow to harden for 1 hour before continuing.

Step 6: Cut 2 Shorter Lengths of PVC Pipe

Cut two lengths of pipe around 6 inches each. Insert one into each of the 90 degree elbows on the vertical (long) piece.

Step 7: Assemble the Coupler

Take the the 3/4" Slip Fit to 1/2" Threaded Reducer. Wrap the threads in teflon tape, making sure to wrap the tape in the same direction you will be twisting the piece into the coupler. Repeat for the hose threaded to 1/2" threaded reducer.

Step 8: Attach Hose Coupler Assembly

Attach the Hose coupler assembly to one of the short pieces of pipe on the Vertical pipe.

Step 9: Attach Toilet Valve to Vertical Assembly

Attach the toilet valve to the short pipe on the Vertical assembly

Step 10: Test Fit in Pool

Place the whole unit in your pool, and check to see if it sits around the right height. Connect it to your hose, but DO NOT turn the water on or it may come appart because the PVC has not been cemented yet. The valve is adjustable, as well as where the float sits, so make sure the float sits about midway in the water.

Step 11: Cement the PVC Together

If the test fit is the right size, go ahead. If it is not, either cut the vertical piece shorter, or cut a new longer one. Cover your work surface with towels or newspaper to prevent getting cement on it. Remove the joints one at a time and apply glue to the end in a circular motion. While inserting the pipe into the fitting, twist the pipe a 1/4 turn. Hold 30 seconds and wipe off excess cement. Repeat for remaining joints. Allow to dry for 2 hours before continuing.

Step 12: Test and Adjust in Pool

Take it out and place it in your pool. Connect the hose and turn the water on. Adjust the height of the valve and location of the float until the water shuts off.

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84 Discussions

Im not sure of the name. My mom had a $100 pool filler contraption that broke. I dissected it and found that in it. I then Shattered it on the ground. I went to the local pool supply store and they actually had a replacement one. It works awesome but cost me $25. i was leaving on vacation that day and I needed to get it working ASAP or I would have gone to Home depot and just made one from a toilet float. water is going in through the top and the white cone helps keep the water from spraying out.


Just want to say thanks for the idea and share my video of mine

HI guys, thanks for all the info, and also all the comments too, very useful post. here is mine, very easy one, I used a side one instead of a bottom connection, i will use it with a timer when i leave the house a few days only, so i wanted one that i can easy put on and off. once again just a few Euros and good to go.


Use a high-quality industrial hose that is in good condition and make sure the water pressure is 60 psi, or less, and it should be fine during a summer absence of a month or two.

I've been an Instructables fan for many years but I must say this is perhaps the best instructable I have seen. It is very economical, it includes lots of suggestions and it has upgrades. To top it all off, it will make me look like a superhero to my wife who maintains our pool and has left the water running too many times to count. We've had our pool for 22 years and I have never seen a solution so easy and efficient. While economy isn’t super important, I am unwilling to spend $30+ for the Hudson value as nice as it looks. I do believe I will build a bracket or some kind of method to secure the device to the wall of the pool. This isn’t so much for allowing it to be in while the l kids are in but to make sure it is properly mounted. I do agree with the post about using a hose intended to contain constant pressure, if and only if you intend to leave it in the pool all the time. As I do not intend to use it that way, I will not initially worry about that. We have several storage boxes around the pool and it would fit nicely in one of them while not in use.

Thanks so much for a great idea! If there was a way to nominate this for an award I would gladly do so.

My pool already has this built in by the skimmer, don't most pools have this already too?

1 reply

Some do, some do not. for those that do not, it is very costly to add one after the fact.

This is awesome, just built mine as well. Testing it in the pool after it has dried overnight.

fantastic! i'm going to use this with a rain barrel to keep my koi pond's water level up.

Just finished mine - works slick. My Fluidmaster float was a loose fit in a 3/4" thread-slip adapter, so I just mixed up some JB Weld, coated the inside threads with it, and it tightened up perfectly. Thanks.

no epoxy the float i got threads fit nice to a 3/4 coupler and as you can see i its an inturnal float so i was able to put it up against the poolside for less chanses to get broke

3 replies

I have searched for hours trying to find that coupler. Is the float 3/4 or 7/8 thread? I have only ever seen 7/8 thread valves, and have never seen 7/8 couplers. Where did you buy it?

i got it from lowes not sure on the threads its made by korky . i just played around in the pvc area putting the whole thing together took it on pvc glued it and pressure tested it and vac tested and was hour long no air leaks