I recently rented a house that has an above-ground water tank. It hasn't been used in at least six months. There is some water at the bottom of the tank and it is black and smelly. Anyway, with the coming water shortage I thought of filling the tank. Actually filling the tank is no problem. Routing the water into the house is no problem. Cleaning the black crap out of it IS the problem. I am too large to physically get in to the tank and scrub it, and I have also seen no drain hole at the bottom of the tank to let the nasty water out. Okay, there is a drain hole, but it has a PVC pipe leading to the house glued into it. So my questions are these: 1. How do I clean out all the black smelly crappy water at the bottom of the tank, and 2. How much damage will I do to the house's water system if I flush the bad water out through the house pipes?

I have no experience at all in cleaning tanks but basic plumbing with pvc is easy, you can cut in to it using a small saw to make a emergency exit and buy a connection again glue it up with pvc glue. as for cleaning i would just throw alot of bleach and dettol in there and flush it out.

If there is any blockage there is this sodium stuff and add hot water to it should clear the pipes with in seconds. Make sure to flush the sodium all out too with cold water after your done

I agree with RakJungTorlae. I'd drain the tank and rinse it out, refill it and add at least the bleach. I'd use about a liter of bleach for anything up to about 25 gallons or so. I'd also run the water to put that bleach into every water outlet in the house including toilets, outside faucets, washing machine, sinks, showers etc. Then I'd let that sit for two hours and thoroughly flush all with fresh water. When I ran the bleach into the house I'd wait until I could smell bleach to know it was there.

If you have to cut your pipe there is a fitting called a union that will fit into a small gap you make by making two cuts in the pipe to create some room. Perhaps YouTube would show you that. It's easy but it needs primer and glue.

Don't let someone sell you a compression fitting to fix the cut because those are best used for sprinkler systems.

Cheers

Do not flush the bad water through the house- especially if you have individual water heaters- can really mess them up- also mixer taps.

Speak to the landlord. If things go wrong it could get expensive and cause health issues.

Actually OP, I would be leaving it well alone. Even if you make a clean break and get most of the muck out, there is still a chance of it siphoning back into your neighbours water supply when you reconnect leaving you in deep strife. Especially if you don't know for sure where the isolation, check valves are fitted.

Just cut the PVC pipe... Flush all the cr@p out the tank and then re join the pipe. Don't use excessive amounts of bleach, it doesn't take much to kill the bugs.. Do a thorough rinse through and you are good to go

Do not flush the bad water through the house

Agreed

Speak to the landlord.

Did that. He said to handle it and send him a copy of the receipt. I can deduct the amount from my rent.

there is still a chance of it siphoning back into your neighbours water supply

I hope not. I do not want to pay for the neighbor's water. Theoretically, each house here has a separate water supply . . . unless someone has tapped in to my water.

Especially if you don't know for sure where the isolation, check valves are fitted.

Actually I do. I know how to change the water input from the mains to the tank and how to keep tank water from entering the house pipes.

Thanks to all for your help. Now I have a weekend project!

Just cut the PVC pipe... Flush all the cr@p out the tank and then re join the pipe. Don't use excessive amounts of bleach, it doesn't take much to kill the bugs.. Do a thorough rinse through and you are good to go

Cut it, lay it down, use whatever you can get to clean.

Best would be a pressure washer,

When rejoining, use two of these screw couplings with O-ring (one for the inlet, one for the outlet).

(cost down to 35 Baht or so for 1/2 inch)

Easy to fix and open whenever you need to clean again.

No glue involved.

Clean the pipes' surface before fixing.

Edited July 8, 201511 yr by KhunBENQ

if my water tank outside had black stuff in it, and no easy way to get it out, I would purchase a new one. ok you can chuck a load of bleach in their clean it out etc, but do you wanna risk it. Purchase new water tank, they are cheap enough.

I would fill the tank first to check for leakage.

Yermanee