Large water storage tanks, why they are used ?

Have you noticed if your neighbors have a large cement ring water storage tank?

What they imply about well recovery rate or well yield?

What does it mean if you see a huge water storage tank at a property?

 

Answer: That the well is a low volume producer of water and you should take note and know that you may not be happy with a low volume water well. The water well system that pumps into a storage tank may not be your idea of a high-volume water system and you are right.

Can we use additional water storage tanks to overcome a well that has a very slow recovery rate or a poor well flow rate? Yes, we can, with some warnings. Very large water storage tanks, are likely to indicate that the flow rate of the well serving the property is very slow, even inadequate by contemporary standards. The rate in gallons per minute at which the well can give water over a sustained period, to be very low, perhaps around one gallon per minute or less.

Very low well flow or well water delivery rates in the 2.5 gpm range or below, simply can't keep up with the rate of water usage in a building during normal occupancy no matter how large a pressure tank(s) you have installed.

Worse, if we have only a typical water tank installed, say a 30 or 40-gallon unit, that tank is designed to smooth the flow of delivery of water to the building as the pump is turned on and off.

A small water tank is not sized to actually store a reservoir of water for the building. So, if your well flow rate is very low, the building will simply run out of water and occupants will have to wait, perhaps hours, for the pump to re-fill the water tank.

Multiple smaller water tanks may also mean that the well flow rate is poor.

A modern solution to poor well flow rate is to install a cascade of two or more individual water pressure tanks to provide a larger volume of water stored at a well site.

A low flow rate well and pump may rely on "recovery" overnight or over many hours.

So, a common solution for a low-flow-rate well is the installation of a very large water reservoir. At older properties the single water tank may have been a large cement ring tank with 1000 gallons or even more capacity.

With a large water tank or multiple water tanks installed to provide this water storage reservoir, the well flow rate can be terrible, but the building occupants won't see its effect since they're working off the cement water storage tank.

Without an understanding of the hydrology of water movement in and out of sand, limestone, dolomite, etc. formation(s) the best guess at flow rate is a Specific Capacity test done by a Licensed Water Professional. Water aquifer formations can either be "Confined" or "Unconfined" in nature and without an understanding of the basics of  Physical Geology it is hard to communicate this concept to you the well owner.

At a low-flow-rate well installation the pump will be designed to run at a slow pumping rate so that the well water flow-rate can keep up with the pump as the pump sends water into the water storage tank.

The building occupants use water out of the tank (with a booster pump) (single stage or 2-stage) and the tank, well and pump recover their water slowly, perhaps overnight.

Low flow rate slow recovery rate wells have a questionable future life expectancy

A final warning about low-flow rate wells: because in many areas water is flowing into the well through cracks in rock below the surface, and because we're starting with an already low recovery rate well, the future ability of the well to give water at all must be questioned. If local water is heavy in minerals, for example, the minerals tend to clog up those rock cracks over time, gradually reducing the water flow-rate into the well still further, until eventually it just stops working.

So, a very large water storage capacity at a property is an indicator of both a low-flow-rate well (poor well recovery rate means the same thing), and an indicator that the future usability of the well at all must be questioned.

Pictured Below:

A 2,500 Gallon storage tank for a Ranch Home in LaSalle County, Texas that we switched a water well into, then pressured into ranch home with an All Brass Flint & Walling Centrifugal Pump. Well Depth is 260' and is drilled into a Minor Aquifer Formation but water is sweet and has no odor before or after tank.

 

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