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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMP SHORT CYCLING
WATER SOFTENERS & CONDITIONERS
WATER TANK REPAIR PROCEDURES
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
This article describes the use of extra or large water tanks to store additional water at properties with intermittent or limited water supply from a low-flow-rate well or intermittent municipal water supply.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
LARGE WATER TANKS - Large Water Storage Tanks, Why They Are Used, What They Imply about Well Recovery Rate or Well Yield
The large indoor water storage tank shown at page top was contributed by reader Craig Revill and was found in a home that was 80-100 years old. We calculated the water tank volume at about 450 gallons.
What does it mean if you see a huge water storage tank at a property? 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, such as the one whose end is visible in these photographs from two different properties, are likely to indicate that the flow rate of the well serving the property is very slow, even inadequate by contemporary standards.
We've found these old steel tanks at older properties in the Northeastern U.S. in situations where the well flow rate, 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.
Large water tanks may indicate that the well flow rate can't keep up with demand
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 our 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 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 1000 gallons or even more.
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 of the water storage tank.
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 to the water storage tank. The building occupants use water out of the tank and the tank and well and pump recover their water slowly, perhaps overnight.
Low flow rate wells or slow recovery rate wells at modern properties use a cascade of water tanks
At newer properties this same approach may be taken to "solve" a low-flow well but instead of a single huge steel tank such as the one in this photograph, the plumber will install a series or cascade of from two to perhaps four or five smaller water storage tanks of perhaps 50 gallons each. If you are looking at a property and see that it has five new shiny blue and pretty big water tanks lined up in the basement you can guess that the well is marginal in its delivery capacity.
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. We explain how people determine the necessary water tank size and volume at WATER TANK SIZE & VOLUME .
OPEN WATER TANKS - gravity fed water systems or pump-up rooftop systems with and without pressure-boosting pumps and water tanks
Readers should also see PLASTIC CONTAINERS, TANKS, TYPES where we describe health and other concerns involving plastic tanks and other containers used for water storage.
See also see PLASTIC CONTAINERS, TANKS, TYPES and Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost. See Wells, Cisterns, & Springs for a discussion of types of drinking water sources and what goes wrong with water supplies.
Frequently Asked Questions (FAQs)
Questions & answers or comments about when, why, & how large water storage tanks are used.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.