any experience with Otto Graf Carat underground tanks for rainwater storage?

Hello Permies,

Otto Graf's underground water tanks are one of the options I'm considering for my rainwater storage system.  More precisely, the 10,000 litres tank, and potentially I'm looking at the Carat S professional package. It is not a cheap option, but I'm considering it among others.

http://www.graf-water.co.uk/rainwater-harvesting/tanks-underground/rainwater-tank-carat-s/carat-xl-underground-tank.html

The water would be for domestic use.  The built-in filter unit and floating extraction unit seems attractive. Not sure what to make of certain features like the Drinking Water Feeding Module, and the fact that it seems to be recommended for only certain uses - namely, washing machines and toilet flushing (even though they promise high water quality)...  Whereas my intention is to have rainwater at every point of use in the house (with the possibility to switching the entire system to mains if/when needed).

I was wondering if anyone here has any experience with the product, in terms of advantages and drawbacks, problems / failures, potential issues that I could expect with such a system.  

Any thoughts would be appreciated !

L_

The only for certain uses is legal liability avoidance.  They can't say what was in the rain, so they can't say the water is safe for drinking.  If you are downwind from a power plant, refinery, major industrial area, etc, you can have some stuff they can't filter out.

IF IT WERE ME:  If I had mains available, I would run it so sinks could be switched separately just in case you want to run them from mains.  I also would use RO or a Berkey for drinking water.  Setting up the plumbing separately initially would help if you have inspections, then you could replumb later.

Levente Andras wrote:,

... my intention is to have rainwater at every point of use in the house (with the possibility to switching the entire system to mains if/when needed).

Sorry, I've just realised that the above sentence is ambiguous to say the least.

What I meant was: separate lines from mains and the water tank will enter the house, where a valve will allow me to switch the whole supply (to all points of use in the house) either from the mains or from the rainwater tank.

In other words: rather than have some points of use supplied only from mains, and others from the rainwater system / mains, I would have all points supplied by only one line, which can be switched at the point of entry to either mains or rainwater.  Decision to switch to one or the other would depend on quality of water that I can obtain in my rainwater system, and the reliability of the mains supply.

Phew !  I hope that's clearer now...

(Background: my house is in a rural village.  The village has its own mains water supply from local springs.  Depending on their elevation, some parts of the village may have supply issues, especially during periods of drought. In addition, the quality of mains water - which currently is quite good - may not be guaranteed in the future.)

I  doubt a dual system is allowed because of the liability of rain water getting into the municipal water supply. When i looked at getting city water, they wanted my well completely disconnected from the house. Valves and backflow preventers wasn't good enough.

If this is your case, plumb the rainwater in and use at as the only source. In a drought, use the city water to fill the tank. A spigot on a separate line that doesnt connect directly to rain lines.

I have used above ground plastic tanks and they were fine. I'm sure the one you posted will do fine. I would be concerned about how to get sediment out of it overtime. I don't use things that pull water out from the middle. I take it out of the bottom. Whatever sediment gets in, i'd rather deal with it now and pull it and filter it out.

wayne fajkus wrote:I  doubt a dual system is allowed because of the liability of rain water getting into the municipal water supply. When i looked at getting city water, they wanted my well completely disconnected from the house. Valves and backflow preventers wasn't good enough.

If this is your case, plumb the rainwater in and use at as the only source. In a drought, use the city water to fill the tank. A spigot on a separate line that doesnt connect directly to rain lines.

I must admit I'm not aware of our local laws in this respect.  We're a bit backward in terms planning regulations, which are in a constant state of flux. Trying to be up-to-date and compliant with them has been very frustrating, especially as enforcement of planning regulations and inspection of new construction in rural areas is patchy. The local council is overwhelmed and unable to cope with these things - it took them over 1/2 a year to send someone over for the handover inspection of my recently finished house. The official didn't seem interested in anything that was below ground and out of sight...

...At any rate, this is an accomplished fact now - I have dual plumbing, with the possibility to use rain water from the underground cistern.  It may turn out that I'll never need the rain water for domestic use - so far, we've been using the village's mains water, softened (using a North Star water softener) and filtered for drinking only (using a Berkey's water filter). I've been using the rain water in the veg garden.

wayne fajkus wrote:I have used above ground plastic tanks and they were fine. I'm sure the one you posted will do fine. I would be concerned about how to get sediment out of it overtime. I don't use things that pull water out from the middle. I take it out of the bottom. Whatever sediment gets in, i'd rather deal with it now and pull it and filter it out.

That's a very good point.  As it happens, my pump also draws water from the bottom.

Thanks for your advice !