domestic water tank challenge

martco

have been fixing up a 150 year old cottage that's seen a couple of renovations I think up to the mid 90's....everyday brings a new "challenge" and as ever yesterday another one raised its head

there's a cold water black plastic domestic water tank looks like 50 gal installed in the most awkward place under a roof pitch crawl space...had to have been built-in to the ceiling as there's no way it's able to come out of it feck knows how I'd even get to a leak if it ever happened!

Anyway, the problem is this attic space is an old dirty uninsulated place, there was plenty of insects/cobs/evidence of rodents before we sorted out the walls and roof repairs, now its as tight as it's going to be but still fairly dirty up there......and the genius that installed this tank forgot the one fecking thing needed - A LID for the tank!?!

I managed to get my head into the gap in the rafters and what I can see is usual silt and it's a bit dirty but nothing really bad like floating bats or anything....I want to give this tank a clean however and try get a lid onto it without going overkill

I was thinking Milton for a day and couple of flushes but reading all sorts....
Milton?
Bleach?
Truma sachets?

all suggestions welcome, just remember I can barely access the thing, to do that I'd have to pull a ceiling and not doing that at this stage

ta

deandean

Every tank I have looked into has a load of crud at the bottom.
Once the outlet connection is a bit above the base you won't get any of it in the water.

I'd only worry about stuff that's floating on top. Once it has decomposed and sunk, it's grand LOL!

Trust you are gonna put a lid on it.

If you do want to clean it I zuggest drain the tank and suck up the crud/water with a wet & dry vacuum cleaner.

intro

Get the cheapest "thin" bleach available, most of which are around 5% sodium hypochlorite. Pour it into the water tank. Run each cold tap until you get a smell of chlorine from the water and then close the tap. When you have the cold system done you could do the hot system. Same thing again, run hot tap until you get a chlorine smell. You may need to top up the chlorine in the main tank depending on the volume of water used to refill the hot water cyinder/system. Leave overnight if possible. then flush all pipes. Run each tap until there is no chlorine smell from the water. Do every tap in turn. You can get test strips to show the presence of the chlorine but if you can smell ok it would not really be necessary. Milton is an expensive way of doing this as it is 1% sodium hypochlorite.

perry stanley

Bearing in mind that (in summer particularly) water stored in tanks , if used in sinks (ie brushing teeth) can be a source of bugs and forms of e-coli.
Is it an option to make it redundant but for the basic 'things', toilets...and so on.
This would lessen the need to be so thorough because once 'cleaned', quite literally the next run of water when cleaner has gone will infect it all over again, little as it may or may not be.

martco

thanks everyone

yes defo making up a lid for the tank so at least when I've cleaned it out I can stop any further risk of contamination...so here's what I'm going to do:
1. do my best to remove any floating crap, I found a good old fashioned tadpole net on a bamboo in one of the toy shops for that
2. dose and rinse out the tank and pipes per @Intro's suggestion
3. lid

@Intro, if ure reading this the only thing I was worrying about was if the sodium hypochlorite would have the potential to rot any seals/ptfe that might be in the circuit, its a mix of copper and that push-fit qualpex. the other item in the equation is a Triton shower unit
I'm thinking if I don't go mad on the quantity of bleach it should be ok

intro

Hi Martco,
Its a pretty standard way of doing this. its a long time since i used it (working abroad at the time) but there was never a problem with leaks after.
I used to have an exact dilution in a handbook but a quick google gave me 3 pints (us) per 100 gallons (us ) to give 200ppm which is 1.4 litres per 83 imperial gallons. So 3/4 litre of thin bleach in a standard 40 gallon tank. You may have to top it up depending on how much it takes to do the cold system and hot system. It would not be very strong but i guess it might change your hair colour! In reality if you can smell the chlorine it shoud be enough.
The other thing is not to discharge all of this to a septic tank. What you could do if it is going to a septic tank is drain the tank through an outside tap or from a hose onto an internal tap before flushing the rest out of the system.
If you can get a plastic cover its better than making a wooden one. I have seen wooden covers that look fine on top and were rotting into the tank and mushrooms growing on the underside. The more crud, as in organic crud (rather than sand) in the tank the less effective the chlorine will be .
Its straightforward enought to do it. Its best if you can leave it overnight to get plenty of contact time.
Probably the worst part will be the heat in the attic!
Good luck.

jack of all

Tank cover is definitely a must, if you cannot get a plastic cover to suit (probably will be unlikely with an old tank) and if you must use wood you should paint it. Undercoat and gloss it, if you can, to prevent the problems outlined by Intro. Alternatively you could wrap a piece of ply with 1200 gauge dpm and staple the plastic edges on the top side (side facing away from inside of tank).

Joe1919

I had similar problem years ago but with the extra problem of a bee hive above tank and the sweet smell of honey off the hot water as some wax and dead bees in water . I used economy bleach after clean out and had to clean copper tank as well as dead bees in tank

If the tank feeds a hot water system as in my case, someone recommended that the system be set at 60 c. Bacteria of the type that harms humans often flourish at 40c (human body temp) and can survive up to 50+ , so beware of thermostats set too low.