Rainwater cistern upgrade - final stage

This final step was to install a winter overflow. We suspect the crack occurred because part of the cistern is above ground which leaves it vulnerable to freezing in winter. So there was little point in fixing the crack without doing something to prevent it freezing. The aim was to install a system where the water level could be reduced to below ground level in winter (when we don't need it much anyway) and raised to full capacity in summer. The solution was an overflow of adjustable height.

Supervisory and photography role was delegated to the one with the swollen foot:

Wouldn't it be so much better if bees would tell you politely that they are trapped between your toes, rather than going for the 'no-one wins' solution of stinging you? I would have been more than happy to help him out, if only he had asked.

Step 1 drill hole at ground level

This involved removing soil at the base so we could get at it with the drill

The decision on where to site this led to an interesting discovery. The original plan was to site it at a corner where it woukd be out of the way. That was until we discovered that the wall at the corner was twice as thick as anywhere else. Why? Because while the cistern is either 6/7 or 8 sided on the outside (it's hard to tell when it's partially burried), it's 10 sided on the inside. Go figured how that was built ☺

So the width of the wall changes in a curious fashion as you move along it.

The end result of this discovery was a location largely chosen by where the wall was thinnest otherwise the drilling would have been impossibke.

Step 2 insert pipe.

This was a standard push fit 40mm plastic drain pipe. Sealant was applied around the pipe in rings and then it was inserted from the inside so that the bulge butted up against the hole, crushing the sealant and forming a seal.
Pipe emerging:

(A pause ensued at this point when the head fell off the sledge hammer and it dropped into the cistern......Plop.)

But eventually the pipe was fully installed:

From this point your options are only limited by your piping creativity.
You can leave it as it is and the water level will stay below ground level (our winter plan)
You can attach a bend and a length of pipe the height of the cistern:

and the water level will come up to the top.
But we don't want it to overflow right in front where we walk so a little more pipe work diverts the overflow to where it can be useful to the apple tree:

But this looks decidedly ugly, so flip it all around and bury most of it underground and its nearly there......

All we need now is a lot of rain to test it.