Greenhouse Thermo Heat Sink (Barrels) water ALSO used as an Emergency Water Back Up for household us

Hello All.
This is my first post here after LOTS of reading the last couple of years. Thanks for all the great education!

I am working on planning an Earth Bermed - Semi Walapini - Heat Sink - greenhouse that I hope to start on in about a year. I am thinking around an 16' - 20' depth and 30' - 40' length, sunken about 3' into the ground, and bermed on 3 sides.

My question is in regards to the water stored in the 55 gallon barrels or IBC totes and it's potential use as an "Emergency Water Supply" I have access to both barrels and totes that I 100% know only every contained food grade ingredients. I have been toying with the idea hooking them together as a 'loop' and circulating the water to help capture more heat.

That got me thinking as we are just starting down the road of trying to "be prepared" for events like power outages, supply chain issues, storm damages etc.... and I started to wonder if the water used for the heat storage could ALSO be used a back up water supply? I realize that I would need to treat it as it 'goes in, or when it 'comes out'. The thought also crossed my mind that we could use THAT water for irrigation in the greenhouse if we wanted to keep it fresh also.

Thoughts? Am I nuts?

Thanks, Dan Dietz

the more you use, the less thermal mass is there to work for you. personally i’d use it only in times of extreme drought when water is scarce otherwise.

It's doable, but there are risks to be carefully managed. I think the biggest risk is Legionella. Thermal water storage would create perfect incubation conditions. The water would have to be handled in a way that prevents inhalation of aerosols and then heated to a pasteruizing temperature.

This has been on my mind a bit too. I've got no answers, but I think there's a lot of "it depends" involved.

How are your tanks being filled and refilled. If the water going into the tanks is coming off the closest roofs, it saves you having to move it around. Water's heavy. If you're paying to pump it, it might be wiser to leave it sit as mass, and run the pumps when it's cheapest to you.

Filtering and tank materials for what you could safely use the stored water for.  Drinking, watering the plants, laundry, etc.

What kind of seasonality does your water have? When would you be draining the tank, refilling it, do either of those overlap with your cold season?