Water Storage Tank Safety, Plastic Contaminants, Relief Valves, Installation & Inspection

  • WELL PUMP & WATER TANK SAFETY - CONTENTS: Water pump and water pressure tank or water storage tank safety devices & advice. How to Buy & Install the Right Water Tank Pressure Relief Valve for Water Storage Tanks or Water Pressure Tanks. Home Water Tank Safety, Water Tank Relief Valves, Water Tank Electrical Switches
  • POST a QUESTION or READ FAQs about water storage tank & water pressure tank safety, features, & controls

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This article describes Home Water Tank Safety:

Water Tank Pressure Relief Valves, Water Tank Electrical Switches, how to use them, adjust them, or where they should be installed. We include a water tank safety checklist and a water storage tank installation checklist.

We also discuss PET plastic water tanks.

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WELL PUMP & WATER TANK SAFETY - Water pump and water pressure tank or water storage tank safety advice

Photograph of a water pressure tank control valveWater tank pressure relief valves are discussed here. We provide safety tips about water pressure tank relief valves and electrical safety around water pumps, water pressure tanks, and water storage tanks.

Article Contents

Water Pressure Tank Pressure Relief Valve

In this photo, the small brass fitting to the right of the black drain valve is a pressure relief valve needed on any pressurized tank. On your water system these components may be located differently.

Tank rupture hazards: can damage equipment or injure someone nearby. Every tank which is pressurized (such as by water or air) should have a pressure relief valve installed - a safety device required by building codes in many jurisdictions.

Most water tanks operate at relatively low pressures, up to perhaps 60 psi. (Higher water pressure in buildings tends to cause leaks at faucets and toilets.)

But in the unlikely event that a pump pressure control is damaged and refuses to turn the pump OFF, pressures in the system, particularly if a submersible (in-well) pump is installed, can become high enough to rupture a water tank. This is particularly true if the tank is old, rusted, or otherwise damaged.

The water tank pressure relief valve shown in our photo (above) is marked indicating that it will open at water pressure equal to or greater than 75 psi. That pressure is pretty standard and you'll see the 75 psi figure on valves used on water tanks and on some tankless water heaters too.

Check with the manufacturer of your water tank to determine if a different relief valve opening pressure is required.

Details about water storage tank relief valves or water tank pressure relief valves are at RELIEF VALVE, WATER TANK

If a pressure relief valve is not installed on your water tank ask your plumber to provide one promptly.

Other Water Tank Safety Hazards

Water Storage Tank Health, Safety, & Sanitation Advice

Plastic water storage tank (C) Daniel FriedmanQuestion:

I've been unable to find on-line information about the safety of using common 1500 gallon plastic water tanks to hold drinking water. Our tank is shaded, but summers are warm and the water often sits in the tank for weeks, especially when we are traveling.

Our tank is 20 years old, but according to web sites now selling drinking water tanks, the plastic is polyethylene terephthalate aka PET.

To my knowledge, we haven't had any problems to date with bacteria growing. I don't taste plastic. We once had a mouse get in and die. Bad smelling water. It cleared up after a few weeks. Probably drank some of it!

Do you have any information or links? - Barbara Stuart

The above-ground water cistern storage tank shown in our photo (above left) is located in San Miguel de Allende, Mexico and is discussed at PASSIVE SOLAR HOME, LOW COST.


As Ms. Stuart pointed out, some water storage tanks are made of plastic polyethylene terephthalate aka PET. Polyethylene Terephthalate (PET, PETE or polyester) is commonly used for carbonated beverage and water bottles.

Some water storage tanks have also been constructed of this material.

PET - Polyethylene terephthalate (PETE, PETP, PET-P) is a thermoplastic polymer polyester plastic resin. plastic water tanks may be a health risk to consumers: Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic. Proposed mechanisms include leaching of phthalates as well as leaching of antimony. Other authors have published evidence indicating that it is quite unlikely that PET yields endocrine disruptors. - Web search 6/27/2010 Wikipedia. PET

Sorting Through the Confusion of Opinions vs. Studies About Plastic Container Materials, Names, Hazards

Researching the health hazards of plastic containers and asking which plastics are safe can give conflicting and confusing results.

Some sources such as the "green" website assert that PET or PETE polyethylene terephthalate and HDPE high density polyethylene plastic containers are "GOOD: Not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.".

These same sources may tag LDPE, PP, PS as "OK", and tagging PVC or V and PS as "BAD - PVC - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen., and BAD PS - According to the National Institutes of Health, di-2-ethylhexyl phthalate (DEHP), commonly found in PVC, is a suspected human carcinogen." - Web search 07/24/2010

There is also confusion about "polyethylene plastic" bottles and tanks. Don't confuse HDPE plastic (high density polyethylene) with PET - Polyethylene terephthalate (PETE, PETP, PET-P) - see What Plastic Was Used to Make My Water Tank (or water bottle)?

Looking at more expert researchers commenting on PET plastic containers:

But recently researchers have raised serious questions about potential health and environmental concerns for PET or PETE plastics. At Reviewers & References see Sax L 2010, López-Carrillo L, et als 2010, Koike E, 2010, for examples.

In April 2010 Environmental Health Perspectives, a peer-reviewed open access journal published by the National Institute of Environmental Health Sciences, Saxreported that

Polyethylene terephthalate (PET) is widely used to make clear plastic bottles for bottled water and containers for other beverages, condiments, and cosmetic products. There is concern that estrogenic chemicals such as phthalates may leach into the contents from bottles made from PET, although PET is not a phthalate derivative. Sax (p. 445) describes several studies suggesting that water from PET bottles can have estrogenic activity in some bioassays and that phthalates might leach from PET bottles. The author notes the difficulties in evaluating these studies, especially in cases where there may have been prior contamination of the water or the containers with estrogenic agents or phthalates.

Sax suggests that the phthalate content of PET bottles, if present, might vary as a function of the acidity of the product and the temperature and duration of storage. Sax also makes the observation that other nonphthalate chemicals such as antimony, which is used as a catalyst in the polycondensation of PET, might also contribute to the endocrine-disrupting activity of products stored in PET containers. The widespread use of PET plastic for a variety of applications suggests that additional research is needed.

The contents of the PET bottle, and the temperature at which it is stored, both appear to influence the rate and magnitude of leaching. Endocrine disruptors other than phthalates, specifically antimony, may also contribute to the endocrine-disrupting effect of water from PET containers.

Conclusions: More research is needed in order to clarify the mechanisms whereby beverages and condiments in PET containers may be contaminated by endocrine-disrupting chemicals.

If your water storage tank is made from Polyethylene terephthalate (PET), and is exposed to high temperatures such as exposure to direct sun and/or in a hot climate, the health risk may be increased. At REFERENCES, below, we include citations of several recent articles discussing health risks from Phthalates and PET containers.

List of Types of Plastics Used for Containers & Tanks

Please see PLASTIC CONTAINERS, TANKS, TYPES for our complete article on this topic.

Sources of Plastic Water Storage Tanks

Some currently-marketed plastic water storage tanks include water tanks for RVs and home or commercial use, constructed of [web search 07/24/2010]

So What Plastic Was Used to Make My Water Tank (or water bottle)?

Please see PLASTIC CONTAINERS, TANKS, TYPES for our complete article on this topic.

How do you identify what kind of plastic was used to make your water or other storage tank or even your plastic water bottle or food container?

Use the simple guide to plastic recycling codes and other plastic tank type identification suggstions at PLASTIC CONTAINERS, TANKS, TYPES [live link given just above] and look for the recycling indicator or label on your plastic container.

Water Storage Tank Safety Checklist

Watch out: be sure that any storage tank is not an attractive nuisance to children or teens, and that the tank is protected from entry - a child or animal falling into a tank could perish.

Chem-Tainer provides these Water Tank Safety Checklists and Advice

Watch out: * EXTREME CAUTION: Consult Customer Service on any applications where continuous use is above 70° F.

Water Storage Tank Installation Checklist

Water Storage Tank Operating Parameters

Water Storage Tank Maintenance Guidelines

Chem-Tainer Industries - original source

Other Water Tank Safety Topics


Continue reading at WATER PRESSURE TOO HIGH: DANGERS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see WATER TANK PRESSURE RELIEF VALVE - separate article: pressure relief valves for water storage tanks or water pressure tank

Suggested citation for this web page

WATER TANK SAFETY at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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