OFF GRID Rain Harvesting System – Part 3 – plumbing and fittings

Layout Tank Inlet Hole Location

large speed square helps lay out the location for the holes in the tank

Then I can mark my center point for the inlet hole.

hole saw drill tank for inlet pipe

I marked this location this way so I could use standard 45 degree elbows to connect the pipe to the surround wall. I tried to position this hole as high up on the tank as possible. Not so high that it would not run into the thread lip where the lid screws on.

Drill Tank Inlet with Hole Saw

hole saw drill tank for inlet pipe

You don’t get a lot of second chances drilling holes in a big tank. So I took my time planning and thinking this through.

hole saw drill tank for inlet pipe

I used a large hole saw for the inlet and overflow pipes. On the slow setting, I drilled until the pilot bit pierced the tank, then clicked the drill in reverse to cut the big hole. This keeps the hole saw from grabbing. And this worked really well.
A rubber grommet fits in the hole and the pipe expands the rubber to make the seal against the plastic watertight. Then I push in a short piece of pipe. It’s tight and a bit of soapy water helps.

Make a Calming Inlet Pipe

assemble and instal the calming inlet pipe in the rainwater tank

So that water entering the tank does not stir up sediment, I’ll run a pipe to the bottom with two elbows to create a calming inlet.
This will keep the water from splashing as the tank fills. I glue up a 90 and 45 fitting and attach it to one end.

assemble and instal the calming inlet pipe in the rainwater tank

Then add a 90 to the other end.
Then set this in the tank and attach it with a stainless steel screw. In case I need to remove it at any time later.

assemble and instal the calming inlet pipe in the rainwater tank

Now, I can drill the hole for the overflow siphon.

Drill the Tank Overflow Hole

hole saw drill tank for overflow pipe

It’s just slightly lower than the inlet hole. And I needed it to rotated around this access hatch wall so it didn’t run into the inlet pipe.

hole saw drill tank for overflow pipe

Then a short piece of pipe is convinced strenuously that this is it’s new home.

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