OFF GRID Rain Harvesting Part 3 – plumbing & fittings

This tank came with a 2 inch bulkhead fitting already installed. It’s for connecting more tanks together and for draining the tank quickly. Or, we can use it for drawing off water.

I’ll be adding a float and screen to this tank so I can draw off the cleanest water that’s just below the surface and away from any sediment in the bottom.

Jump to:

Off-Grid Rain Tank Part 1 – Pour the Tank Foundation
Off-Grid Rain Tank Part 2 – Build the Tank Surround
Off-Grid Rain Tank Part 3 – Tank Plumbing and Fittings
Off-Grid Rain Tank Part 4 – Install a Solar Powered Pump

adding large ball valve to bulkhead fitting on tank
Rainwater Harvesting Tank - plumbing, fittings, float, valves [OFF GRID]

See the Youtube Video Part 1 or Part 2 or Part 3 or Part 4

Off Grid Rainwater Harvesting System – PART 3: plumbing and tank fittings

(this is a transcript from the video)

I’ll add a ball valve to this existing bulkhead fitting. I first add a reducer down to one and a half inches. I didn’t have channel lock pliers big enough for these so I used the biggest wrench I had. Then I’ll add this short nipple, and then the ball valve.
Before I can add the float and screen I need to assemble the parts first. I BOUGHT some of the tank parts and decided to MAKE some of them from existing fittings.

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Float Hose Assembly

attaching float and screen to flexible hose

I cut the float hose down to a length I though appropriate for the height of this tank. About 2 feet taller than the tank I thought would be good. There’s a barbed fitting that goes into the inside part of the bulkhead fitting first. Then the clear flexible hose goes onto that. It was a tight fit and tough to get this on, even with some soapy water as a lubricant. And a stainless steel hose clamps secures it.

attaching float and screen to flexible hose
attaching float and screen to flexible hose

Then the screen and float goes on the other end. And a lanyard is tied to the float. This will keep the screen up off the bottom of the tank when the water level gets low.

adding rope lanyard to float valve

I’ll need to drill a hole in the tank for a bulkhead fitting for the hose that’s connected to this float. It will be around the back at the southeast corner. I’ll use a hole saw for this and drill this hole 4 about inches off the bottom.

Drill into Tank with Hole Saw

hole saw to drill tank for bulkhead fitting

Getting the bulkhead fitting through this hole can be tricky. I first screwed in a barbed fitting into the bulkhead fitting. Then I tied a string to the barbed end. And taped it too.

placing the float flexible pipe for the tank supply line

The other end of this string is taped to the end of a pipe.

placing the float flexible pipe for the tank supply line

Then this pipe is set in the tank with the string end resting on the hole I drilled. I then carefully remove the tape and pull the string through the hole.

placing the float flexible pipe for the tank supply line

Feed String through Hole

placing the float flexible pipe for the tank supply line

I remove the pipe from the tank and lay in the hose and float assembly. Being sure that the end of the lanyard on the float is still outside.

placing the float flexible pipe for the tank supply line

I now pull the string to bring the bulkhead fitting through the hole and attach the nut. I snug this up with a wrench.

threading on the barbed fitting for the bulkhead attachment

I’ll be connecting this fitting to the mini pump house later. But for now I’ll add a ball valve so I can make the tank water tight. I detailed the construction of the pump house box in Part 2.

ball valve in bottom of rain tank

To find the best spot for the tank inlet I sighted down a large speed square. I lined up one edge to the curb and marked the point where the 45 degree edge contacted the tank.

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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