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Simple water inlet design for a courtyard tank

December 22, 2020 — BarryK

I grew up in a rural location, without scheme water. There was one huge concrete tank, that collected rain water. We had no qualms with drinking that water, nor water from any other rainwater tanks.

These days it is deemed inadvisable to drink rainwater. Anyway, I don't want to drink it directly, but for the kettle, for making tea and coffee. I also boil water then cool it and keep in the fridge for drinking. I would rather use rainwater -- suspicious about what comes out of the tap.

I know that rainwater is said to have pollutants in it, from the atmosphere. That would depend where you live. I live very close to the coast, and most rain-bearing weather comes from the direction of the ocean, so should be relatively pure. Also the surfaces on which the water flows and is collected, are factors. The roof is clay tiles.

I bought a small tank, 720 litres, which is 190 gallons. Good enough, got it delivered to my backyard. But then, how to connect it to the downpipe?

Devised a simple solution, so thought to post it here, as it might be useful for anyone else browsing the web looking for ideas how to do it.

I made it with 50mm PVC pressure pipe and fittings, here it is:


...only difference from that photo, is I stuck a small length of pipe underneath near the 45 degree elbow, to hold it up more securely.

The top of the tank has a screw-on lid, with a leaf-strainer and mozzie-barrier inside. It was easy to cut a round hole:


But the other end, connection to the downpipe, that is a challenge. I wanted it to be variable, so that when the tank gets full, water can be diverted to flow down the downpipe and not into the tank.

But firstly, cutting the round hole in the downpipe. I know it is due to my inexperience, but when I used the hole-cutter attachment to the electric drill, the central hole started to "wander" and the hole being cut became erratic. So, I resorted to a nibble-tool. Have one of these from my electronic construction days, works fine on thin galvanised steel:


The idea I came up with, to vary water diversion, is a pipe-joiner, that can be turned. The pipe that inserts inside the downpipe looks like this, a cutout-section:


Then I riveted a piece of 0.5mm thick aluminium:


The idea is that the aluminium flanges can be bent inward, for insertion of the pipe, then once inside, can reach in and push them out again. Yeah, that worked.

Perhaps a heavy downpour will bend those flanges. I could have bought some thicker metal, but then, so what if they bend? Even if only half the water gets diverted into the tank, that should be enough. It is a small tank. Perhaps then, no need for those flanges.

It came together and installed OK, but I wonder about that one-in-ten year downpour? If the flanges are turned to vertical, thus minimising water diversion to the tank, there will be a partial blockage in the downpipe. So what happens if the water backs-up, right back to the gutter?

My place has high-front type gutters, with slots cut in the front so that water overflow will be out the front and not back into the eaves, as this photo shows:


That is probably good enough protection. Even if water does flow back into the eaves, it will, at worst, flow into the wall cavity. My place is double-brick, so the inside wall won't perish. Even so, not something that I would want to happen.

I notice that most new houses built in Perth do not have eaves, the gutter is mounted right on the outside wall, so that extra runoff protection is not there.

I could maybe insert something further up the downpipe, to vent-out excess water. Or maybe that is overkill.

EDIT 2020-12-24:
Here is a photo of the completed pipework, showing the small piece of pipe glued on to support the 45 degree elbow:


EDIT 2021-01-02:
At the downpipe-end, the pipe-joiner can be turned, so as to divert the water either into the tank or to continue down the downpipe. I have a tube of "heavy industrial grease", that I applied to make it easier to turn the pipe-joiner, however, later on reconsidered -- ideally I should find a grease that is rated for potable-water.

There are some available, and I purchased HydroSeal tap lubricant:


Bunnings also have another brand, Kinetic tap lubricant:    

Tags: general