Water tank

[Lhasa]

We are coming over after 2 years away, our outside water tank has had the lid tightly on so no debris has got in, the question is, is it just a case of running the water through the system and allowing tank to re fill with fresh water? We don't use the water for drinking by the way!!

[MnM]

Which tank are you talking about? Our ground tank has one small hole about 5mm diameter on the neck of the tank just under the lid which i assume is for minute pressure / overflow relief to stop the tank bursting if the inlet ball valve doesn't stop completely. If so you will have some dust ingress or even a small termite or 2. I found a small yellow frog in ours once when I drained it. Either way, you may be ok to flush the system through if you need to as you said you don't drink the water. If however your water is yellowy in colour and smells, you may have a build up of Sulphur Dioxide which i understand needs a bit more treatment.

[Lhasa]

It is a large white cylindrical plastic tank above ground on legs, new about 5 years ago.

[thornaby]

If the water has been stagnant for two years I would definitely chlorinated the entire water system, cold tanks, hot tanks, toilets, shower heads, taps etc. Better safe then dead!

[Groucho]

If the water has been stagnant for two years I would definitely chlorinated the entire water system, cold tanks, hot tanks, toilets, shower heads, taps etc. Better safe then dead!

To achieve that, simply turn off the water at the meter, add some bleach/chlorine (an egg cup full is enough) and then open up all your taps and showers etc and pump the water around the system until it runs dry, then turn off all taps. Then refill from the mains. When the water tank has been refilled, check the lower tank and kitchen sink water for any smell of bleach, repeat process (without bleach) until all trace of bleach smell has gone.

[Groucho]

Unless you drink from the toilets, they don't need treating..

[thornaby]

All standing warm water can be a source of legionella bacterium. It is transmitted in fine water mist even flushing a toilet. Shower heads are a definite source. Regarding advice given to chlorinate the system I would advise not just running water through the system but leaving the solution in the system for a little while to allow the chlorine to do its job and then flush. I would isolate the water at the tank, empty the house completely of all water, fill all pipes with chlorinated water, let it stand, drain then flush. On modern installations the top cold water tank is not pumped out but empties by gravity so even when the pump stops that tank will need to drain. Shower hozes and heads should really be removed and immersed in the chlorine solution. Legionella is a killer and is caught by inhalation of infected water.
I estimate my total volume of water in my house is around 6000 litres to achieve the required level of chlorine would need a litre of bleach. Its recommended that it stands in the system for around 20 hours which may be impractical for most people but giving it some time to be effective is very important.

[jofra]

Thanks for the tips and advice; we've been unable to come over since 2019, we did have all this in mind but the detailed advice is extremely useful ,and (pun intended) quite possibly a lifesaver...
in 2019, holiday was extended by six weeks due to OH in ICU with pneumonia and blood infections...
... and that was a few months before Covid appeared in the world.....
An interesting time....