Why 20,000 litres of water had to go

Our house has beside it a concrete tank with around 20,000 litres capacity. Rainwater comes off the roof, through a first flush diverter that helps keep it clean of debris, and then into the tank. When we turn on a tap in the house the pump on top of the tank runs, pulls water from near the bottom of the tank and feeds it to the tap.

It's a great system that certainly makes us aware of whether or not it's rained recently and how much water we're using.

Until things go wrong.

A few weeks ago while I was showering I thought something smelled odd. Thanks to being unwell and some stuff going on, I hadn't cleaned the drain for a bit so figured that must be the problem. A good clean didn't fix things and over the next week the smell grew into a stench.

After some Internet searches which suggested various possible causes I went and stuck my head in the water tank: phew! That smelled bad and was definitely the source of the problem.

I bought water treatment (hydrogen peroxide with a little silver) and added that. Maybe the smell abated a little. I added more, for a shock treatment. We still had a problem and started buying expensive bottled water (~1 litre per dollar) for drinking.

Next up: clean the gutter. I tried asking around for someone to get on the roof and clean the gutter for pay, but that brought zero results. Finally, last weekend, I did it myself. I climbed the ladder to the one spot I could reach, pulled out a big clump of grass, and by stretching out one arm with my iPhone in it was awkwardly able to take a photo. The gutter was an inch thick in gunge. Yuck!

The gutter was full of gunge.

After disconnecting the first flush diverter from the tank, I then taped the gutter cleaning attachment and garden hose to a long pole and walked along below the gutter with arm stretched high, doing my best to wash out the gunk. I still need to go back up the ladder with camera to see how successful I was, but a lot of dirt washed out of the bottom of the diverter.

Next up was a test for E. Coli from the closest water testing lab in Palmerston North. They shipped me a sterile sample bottle, an ice pack and a polystyrene container. I followed the instructions for cleaning the tap, running water for a while and then taking the sample. Then I had to make a special trip to Palmerston North to get the sample back to the lab within 24 hours. Our rural delivery postie is excellent, but the sample wouldn't have arrived within the 24 hour period.

The lab culture the sample for 24 hours and then examine it with a microscope and count the bacteria.

Our results were not good. E. Coli should be below 1 per 100mL, our count was 11.

I contacted our local water supply guy, Reggie, who gave me a contact for a company who clean out water tanks. They came the next day. First they pumped out all the water from the tank — our was brim full, so that was 20,000 litres. Then Russell squeezed himself through the access hole, climbed down the ladder and vacuumed out the gunge from the bottom and walls. The gunk was extracted through a long hose back to the truck. Vacuuming was followed by water blasting and more vacuuming until the interior of the tank was spotless.

 Gunge on the floor of the tank, plus assorted hoses and a ladder.
Russell squeezing into the tank.
Russell uses the waterblaster. The floor is getting cleaner. Clean white floor in the tank.

By that time Reggie had turned up with 14,000 litres of clean fresh treated water from the artesian source at Ōtaki (~46 litres per dollar). While the tank filled, Warren from the cleaning company added a strong concentration of hydrogen peroxide to dose the water and help clean out the pipes through the house.

Clean clear water.

Look how clean and see-through that tank full of water is!

Once everything was finished I had to turn on each tap in the house in sequence and let the water run for 5 minutes.

Our house was built in 2014 and we've lived in it full time for just on 4 years. While we've had to have a couple of tank fills because the water was running out over summer, this is the first actual trouble we've had with it.

Apparently there wasn't anything terrible in the tank: no rotting possums or whatever. It was just accumulated straw that birds had dropped in the gutter, along with sand and pollen and other wind-blown debris, plus, probably, a good deal of bird poop.

Today I had a glorious shower in crystal clear odour-free water!

Miraz Jordan @Miraz

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