Valved Out Water Distribution Tank for Winter - Full or Empty?

[77JQX]

Hi all, I want to get your opinions on our idle water tank. We have a 2.5 MG (150 foot dia by 20 feet tall) welded steel ground level water tank that we take out of service every winter. In our climate, ice would definitely form on the surface, but it wouldn't freeze solid. Last winter we left it full, and then drained and disinfected it in the spring, with no apparent damage. But maybe it's better to drain it first before winter. What's your opinion/experiences?

Thanks.

 

[coloeng]

I've never left a tank out of service all winter, but it seems that you could get some damage to the interior coating from the ice as it freezes and expands along the side of the tank.

 

[bimr]

In addition to the potential for damage from ice, you have a risk of contamination from microorganisms growing in the water and on the tank walls. One would think it would be more difficult to ensure that the tank is clean prior to putting it back into service.

The risk of corrosion is also substantially greater with moisture in the tank. You have the potential for MIC. I believe some facility owners install temporary dehumifidication equipment in out of service equipment. If you decrease the humidity below 40%, there is not enough moisture to support corrosion.

 

[77JQX]

Thanks guys. I appreciate your input.

 

[ch81pc]

We usually drain anything that will be left for greater than 48 hours. Summer or winter. If you do get a cold one the cost of repair will be much more than the time or hassle to drain.