Water – should I split the water tanks for harvested rain water and ground water

water

Water become challenging source in my native (Tamilnadu, India). While I build new home, it makes me think about saving the rainwater.

Ground water(borewell) is the only water source for us. This also having chance to dry on summer. So I like to use the rain water in efficient way.

Is it good to mix the ground and rain water? or should have two separate water storing tanks(underground). Which one is cost effective?

I was thinking to use the two tanks for two different purpose.

Rain water (After basic filtering)

Toilet
Washing
Terrace Garden
Kitchen Sink

Ground water

Drinking (Purified)
Both
Cooking

Needless to say, I also plan to save the good water from kitchen sink(double sink method) and purifier waste water in barrel for ground garden plants.

So please advice me?

Best Answer

Rain water has (practically) no electrolytes. We've all heard that rainwater is acidic, but realistically, that is only relevant on a larger, ecological scale (tons of slightly acidic water will cause erosion). More importantly, rainwater will contain nitrates, oils, and other organic chemicals, and rainwater will contain lots of microorganisms, which will be difficult to filter out with an ordinary (ground-water) filtration system. Common ground-water filters are between 5 and 20 microns. Filtering water is extremely helpful for removing bacteria, but the water is still not sterile. Holding the rainwater may allow growth of bacteria, if the rainwater is "nutrient" rich.

The earth filters out nutrients and bacteria. It's not a perfect system, but groundwater is drinkable (usually after basic filtering). Rainwater should not be poured directly into ground water. Keeping the systems isolated would keep contamination minimalized. In terms of cost, try to think of this as rainwater will pollute the groundwater and could possibly ruin the well. Rainwater treatment can make it potable/drinkable, but I would reserve that option for the worst case scenario unless you have a good treatment system.

At a minimum, rainwater treatment (to make it potable) should include coarse and fine (5 micron) filtration, chlorine and UV sterilization, and carbon filtration.

I would do this:

Rain water (in order of priority)

Toilet

Garden

Outdoor hose

Ground water (in order of priority)

Drinking (Purified)

Cooking

Kitchen Sink

Washing Dishes

Bathing

Laundry

The list is prioritized such that if groundwater is low, then laundry could be done with rainwater. If things get bad, you could use rainwater for bathing. I would try to avoid washing dishes and cooking with rainwater. I would drink rainwater if my life depended on it.

Related Solutions

Water – How to keep two water tanks have maintain the same water level

Note: this answer is for pressurized plumbing of two hot water tanks. Rereading the question I'm pretty sure it's an incorrect assumption so I'm only leaving it here in case it helps someone with this problem.

The typical way to do this is to run the two tanks in serial instead of parallel. You would connect the output of one tank to the input of the other. I've seen this with a solar and electric tank combination. The solar tank was there to preheat the water, and the electric was the second tank that would run on cloudy days. Connecting the two tanks is quite complicated if you need the ability to bypass either tank. Here's a quick ascii art of what I've seen:

         +----X------+--- Hot
         |           |
Cold --+------X----+ |
       | |         | O
       O +----O----+ |
       | |         | |
       C H         C H
       WH1         WH2

The X are closed valves, O are open valves, C is cold input to a WH, H is hot output from a WH. The valve setup that is shown here is for the cold input for the home to go to WH1, back out the hot, into WH2, and back out the hot to the hot line for the house.

You could simplify this if you don't need the ability to isolate one of the water heaters:

Cold --+             +--- Hot
       |             |
       O +---------+ |
       | |         | |
       C H         C H
       WH1         WH2

The nice thing about having the water heaters setup in serial is that you can completely turn one off and still have hot water available to the entire home, just in lesser quantity. And in times of high demand, having both heaters running can get the water back to the high temperature twice as fast.

Water – install a hot water recirculation pump if I have a reverse osmosis filter

I suspect you have a set-up like this?

enter image description here

You are concerned that when the water gets pumped back into the "water heater" it could possibly pollute your main water line?

The only thing I could suggest is putting a check valve on the "cold" water supply so that it can only supply fresh water. That is helpful if the pumps output pressure is higher than your supply pressure (This could happen on someday with low supply pressure or if you do not have main water pressure regulator)

enter image description here

In this situation the return is a dedicated port on the "water heater/boiler" and there should already be a check valve/pressure regulator/non return valve just before the water heater. So the rest of the house will run just on the cold water supply and never get any recirculation contamination.

Best Answer

Related Solutions

Water – How to keep two water tanks have maintain the same water level

Water – install a hot water recirculation pump if I have a reverse osmosis filter

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