Plumbing · Lesson 7 of 13Intermediate7 min read

Water Quality and Safety

Plumbing doesn’t just move water; it can change it. Old pipes can add lead, a warm water heater can grow germs, and a well can pick up whatever is in the ground. Here’s what the health agencies say to watch for, and what to do.

Lead in drinking water

EPA is blunt about lead: there is no known safe level of lead in a child’s blood, and the health goal for lead in drinking water is zero. Children six and younger are the most susceptible.

Lead usually gets into water from the plumbing, not the source. EPA explains that lead enters drinking water when plumbing materials that contain it corrode. Where a home has a lead service line, the pipe from the main to the house, that line is typically the most significant source. Lead pipes are more likely in older cities and in homes built before 1986. In homes without a lead service line, the most common problems are brass or chrome-plated brass faucets and plumbing with lead solder.

EPA: lead service lines are typically the biggest source where they exist; otherwise the most common problems are brass or chrome-plated brass faucets and lead solder. Lead pipes are more likely in homes built before 1986.

What EPA says you can do

Find out what your service line is made of. Ask your water utility, or a licensed plumber. EPA’s Protect Your Tap guide walks you through a quick check where the line enters the house, using a coin or key and a magnet.
Run your water to flush the pipes before drinking, especially after it has sat for hours.
Use only cold water for drinking, cooking and making baby formula. Boiling water does not remove lead.
Use a filter certified to remove lead. EPA’s consumer tool points to filters certified for lead reduction against both NSF/ANSI Standards 53 and 42.
Clean your faucet’s aerator regularly.
Test. Testing is the only way to confirm whether lead is in your water. Use a certified laboratory and follow its sampling directions; EPA puts the cost at roughly $15 to $100.

Public water systems have to act when lead levels are high: under EPA’s rules, if more than 10 percent of tap water samples exceed the action level of 15 parts per billion, the system must take additional steps.

StopLead service lines are a job for the utility and licensed pros

Replacing a service line means digging to the main, working on the utility’s side of the line and following its rules. Call your water utility first; EPA says the utility or a licensed plumber can help you find out what your line is made of. Don’t sand, cut or disturb old lead pipe yourself.

Private wells

About 87 percent of Americans get water from a public supply, USGS says; most of the rest drink from private wells. EPA’s drinking water rules don’t apply to private wells, and the CDC notes that government officials do not regulate, treat or monitor them, so the owner is responsible for the water’s safety.

The CDC says to test your well water at least once each year for total coliform bacteria, nitrates, total dissolved solids and pH, and to ask your health department about other germs or chemicals common in your area. Test more often if there are problems nearby such as flooding, land disturbances or waste disposal sites; if you repair or replace part of the well system; if the water’s taste, color or smell changes; or if someone in the home becomes pregnant or a child comes to live with you. Use a state-certified laboratory.

EPA adds a few habits: keep a well cap or sanitary seal on the well, don’t cut the casing off below the ground, inspect the casing for cracks, and keep hazardous chemicals out of septic systems.

Hard water

USGS defines water hardness as the amount of dissolved calcium and magnesium in the water. It’s measured in milligrams per liter as calcium carbonate: 0 to 60 is soft, 61 to 120 moderately hard, 121 to 180 hard, and more than 180 very hard. Hardness isn’t a health concern, USGS says, but it is a nuisance. Soap reacts with the calcium to form soap scum, and when hard water is heated, calcium carbonate deposits form. That scale can shorten the life of equipment, raise the cost of heating water, lower the efficiency of electric water heaters and clog pipes.

A water softener trades the hardness away. EPA explains that a cation exchange softener removes calcium and magnesium ions by exchanging them for sodium (or potassium) ions, then periodically flushes the captured ions out and recharges with salt. That regeneration can use 25 gallons of water or more a day, up to 10,000 gallons a year, and EPA’s WaterSense program decided not to label softeners, citing concerns about how the salty discharge affects wastewater treatment.

Your water utility’s annual water quality report usually lists hardness; a lab test tells you for a private well.

Filters and treatment

A filter is only as good as its certification and its upkeep. The CDC suggests checking that a filter is certified to the standard for what you want removed, such as NSF/ANSI Standard 42 for taste and odor, Standard 53 for health-related contaminants such as cysts and lead, Standard 58 for reverse osmosis and Standard 62 for distillation. NSF International, an independent organization, keeps a database of certified products.

The CDC also points out the limits. Most home filters, like pitcher and refrigerator filters, are not designed to remove germs. Point-of-use filters treat water at one tap, usually the kitchen sink; point-of-entry, or whole-home, filters treat all the water coming in, and if a whole-home filter removes the chlorine your utility adds, more germs may grow in your plumbing. Change cartridges on the manufacturer’s schedule; a neglected filter can grow germs of its own.

Filter standards the CDC mentions
Standard	What it covers
NSF/ANSI 42	Taste and odor
NSF/ANSI 53	Health-related contaminants such as cysts and lead
NSF/ANSI 58	Reverse osmosis systems
NSF/ANSI 62	Distillation systems

Germs that grow in plumbing

Some bacteria live in building plumbing itself. The best known is Legionella, which causes Legionnaires’ disease. The CDC says it grows best in water between 77 and 113°F and in slowly moving or stagnant water, and people get sick by breathing in small droplets, such as shower mist. The CDC’s steps for homes and rentals: keep the water heater at or above 120°F, flush faucets and showerheads that haven’t been used for a week or more, and flush the water heater as its manufacturer recommends (Lesson 5 weighs this against scalding).

Cross-connections and backflow

EPA defines a cross-connection as a point in a plumbing system where something that isn’t drinking water could come into contact with the drinking water. A garden hose lying in a bucket of weed killer, a hose in a pool, or a sprayer on a utility sink are all cross-connections. If pressure in the main drops, as during a main break or heavy hydrant use, water can be pulled backward through them. That’s why codes require backflow devices such as hose-bibb vacuum breakers and air gaps (Lesson 2), and why you should never leave a hose end sitting in a bucket, pool or chemical.

Check yourself

Tap an answer to check it, or open “Show the answer.”

According to EPA, what is typically the biggest source of lead in water where it exists?
Show the answer
A lead service line. Lead service lines are typically the most significant source where they exist.
Does boiling water remove lead?
Show the answer
No. No. EPA says boiling does not remove lead. Use cold water and a certified filter.
How often does the CDC say to test a private well for total coliform bacteria, nitrates, total dissolved solids and pH?
Show the answer
At least once a year. At least once a year, and more often when something changes.
Water at 150 mg/L as calcium carbonate is…
Show the answer
Hard. 121 to 180 mg/L is hard on the USGS scale.
Which NSF/ANSI standard does the CDC list for cysts and lead?
Show the answer
53. Standard 53 covers health-related contaminants such as cysts and lead; 42 covers taste and odor.

Go deeper

U.S. EPA: Basic Information about Lead in Drinking Water EPA: Basic Information about Lead in Drinking Water.
U.S. EPA: Protect Your Tap: A Quick Check for Lead EPA’s Protect Your Tap guide to checking your service line.
CDC: Guidelines for Testing Well Water CDC: Guidelines for Testing Well Water.
CDC: About Choosing Home Water Filters CDC: choosing a home water filter.
USGS Water Science School: Hardness of Water USGS: Hardness of Water.

Sources

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A free course from Teddy Rook Book. It explains how plumbing works in general and follows U.S. sources; your local plumbing code, the authority having jurisdiction and manufacturers’ instructions are the final word.