I was getting sick of topping up my pool during some dry hot weather, so thought I'd knock up an automatic pool filler.

Now a pool is really like a big toilet cistern: which is essentially what I've built.

Parts List

100mm storm water pipe
100mm end cap
Cistern mechanism (get the enclosed float telescoping type)
Braided hose for water connction
Conduit bulk head grommet
PVC glue, drill, saw

So how do you get the water into the pool? I happened to have 25mm corrugated conduit coming from my pool light, so I threded the wires through the filler mechnism and used it to deliver the water.

Step 1: Assembly

Assembly is very staight forward. Use a hole saw to cut holes for the cistern mechanism and pool water feed.

Cut the 100mm pipe to suit. Test assemble and when you are happy the cistern mech is not jamming, glue the pipe and end cap together. The cistern meck will will fit the braided hose without an adapter. Not shown is a quater turn stop cock connected to the other end of the braided pipe (dont forget to use PTFE tape). Connect the pool water feed and mount.I mounted the mechanism with stainless steel clamps under my deck next to the pool.

Use the telescoping function of the cistern mech to set the pool level.

The filler has been working for 6 months now without any issues.