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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER CONSERVATION MEASURES
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 CHLORINATION & DISINFECTION
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
This article describes rooftop water tanks and cisterns, where they are used, how they work, and the use of booster pumps to improve water pressure in buildings with rooftop water storage tanks. We also discuss using a booster pump to improve building water pressure in buildings with weak municipal water pressure or a weak rooftop
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Rooftop water storage tanks In some areas, Mexico, for example in our photo (above-left), rooftop water reservoirs are supplied intermittently with water from a water main in the street.
The rooftop water storage tanks in this photograph from San Miguel de Allende in Guanajuato are being used both to accumulate a water reservoir so that water is always available to the building, and to supply water at a useful pressure.
Our page top photograph of a large rooftop water storage tank was taken in Manhattan. Rooftop storage tanks atop tall buildings have been in use for hundreds of years - this one was constructed of wood with iron bindings and is used to provide good water pressure to fixtures in the multi-story building it serves.
See details at CISTERNS.
Water is pumped to the rooftop tank from its municipal source, then redistributed at good pressure to the points of use in the building below.
When passing through New York City, look at rooftops and you'll often see these tanks still in use. This sketch shows how a rooftop tank might be constructed, though this particular sketch has the tank next to a well.
Reader Herman Voegel has pointed out that an up-and-coming area of storage containers includes spun-plastic tanks.
The plastic water tank in our photo (left) is used on ground level or on rooftops.
see PLASTIC CONTAINERS, TANKS, TYPES for details about using plastic tanks or containers for water storage.
General HDPE containers come in all shapes and sizes and are quite rugged and relatively cheap compared to using typical 12-gauge steel home heating oil tanks.
The ruggedness of HDPE plastic containers comes from their material density which is typically at a minimum specific-gravity of 1.7, and for heavy-duty at 1.9.
These tanks may be used for storing certain liquids besides water. But home heating oil has not yet been approved for storage in HDPE tanks, basically for two reasons:
However, fixes have been put in place to properly address these problems. UV-light is checked by using special color additives that prevent their light from penetrating and degrading the plastic walls. Permeation or seepage of oil through container walls is checked by coating them with fiberglass.
Unfortunately, even with these fixes, HDPE plastics for heating oil storage have yet to be universally approved and accepted.
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.
Attic Water Storage Tanks or Attic Cisterns
Attic Cisterns or water tanks are installed in some buildings to perform the same function as rooftop-mounted water tanks.
Other smaller attic containers that look like a water reservoir may have been just an expansion tank for the heating boiler system.
Cisterns in basements or attics are an open-type water storage reservoir found indoors, and are discussed further at CISTERNS.
A cistern was generally placed where it could be fed by gravity from roof or surface runoff, but any indoor open topped reservoir of water could be called a cistern.
See SOLAR WATER HEATER ANTIQUE for another example of an attic water storage tank.
Water storage may not be on the rooftop nor in the attic. Cisterns or other water storage containers are often located in the basement or courtyard of buildings where they collect rainwater for future use. In the U.S. cisterns were often located in the basement of a (pre-1900) home. See details at CISTERNS.
In a seasonally damp climate such as New York, an in-use basement cistern would certainly be a likely source of unwanted building moisture and would thus be a risk for problematic mold growth.
In arid areas such as the U.S. Southwest and parts of Mexico, very large cisterns are often placed in a courtyard where they collect rainwater for use during the dry season.
The above-ground water cistern storage tank shown in our photo (left) is located in Mexico and is discussed at PASSIVE SOLAR HOME, LOW COST.
Rainwater for this cistern is collected from a near-flat rooftop and channeled to a large fiberglass holding tank - the blue tank in our photograph, (above left).
Piping also permits directing water into this tank from a well-fed cistern located atop the concrete block tower).
The tower's height provides water pressure to the building. Currently water is taken out of the bottom of this tank by a simple tank drain valve and hose attachment; to supply this water upwards to the building plumbing fixtures or perhaps to the cistern, a small electric pump will be installed.
See rainwater collection and storage cistern details at CISTERNS.
On low buildings or where the water tank is not high above the point of use some systems install a water pressure booster pump and tank. A water pump (WATER PUMPS, TANKS, DIAGNOSTICS) and probably a water pressure tank (WATER TANK BLADDERS & CAPTIVE AIR) will certainly be needed for ground-level or below-ground-level water storage cisterns.
Water pressure booster pumps and tanks may be installed in buildings where municipal water is supplied,
located on rooftops or anywhere in a building, so
don't assume that just because you see a pump and tank that the building is served
by a private well.
See WATER PRESSURE LOSS DIAGNOSIS & REPAIR for details on how to correct low water pressure in a building.
We discuss water pressure booster pump and tank systems in detail at PUMP, WATER PRESSURE BOOSTING
Readers of this document should also see 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 and see Wells, Cisterns, & Springs for a discussion of types of drinking water sources and what goes wrong with water supplies.
If you're looking for information on types of septic tanks see our Septic System Design which includes articles about various types of septic tanks, steel, concrete, plastic, etc. The illustration at page top is courtesy of Carson Dunlop, Inc. in Toronto.
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