Hard Water Test

Who should get a hard water test

The U.S. Geological Survey (USGS) gives how much dissolved calcium and magnesium is in your water as the simple definition of water hardness. Hard water is high in these dissolved minerals, and USGS calls hardness a property of water that is not a health concern but can be a nuisance. So this test is about your plumbing, your appliances and how well soap works, not about whether your water makes you sick.

You see the signs. USGS describes what hard water does around the home:

• After washing with soap, your hands feel like they have a film of residue on them. In hard water, soap reacts with calcium to form soap scum.
• You need more soap or detergent to get your hands, hair or laundry clean.
• Glasses come out of the dishwasher with spots or a film on them.
• Scale builds up in your water heater, pipes, fixtures or coffee maker. USGS says that when hard water is heated, solid deposits of calcium carbonate can form.

These signs tell you hardness is likely. A test tells you how hard your water is, which is the number you need for any decision.

You are thinking about a water softener. Penn State Extension advises having your water tested by an independent lab and finding its hardness class before you decide how much softening you need.

Your water comes from a private well. USGS explains that as groundwater moves through soil and rock, it dissolves small amounts of naturally occurring minerals, so if calcium and magnesium are in the soil around a well, hard water may reach the home. In a USGS study of domestic wells across the country, hard water was prevalent in the east-central and western United States. The Michigan Department of Environment, Great Lakes, and Energy (EGLE) lists hardness among the standard water quality concerns for private wells.

You are testing for iron. The Minnesota Department of Health (MDH) says that in addition to testing for iron, it can be helpful to test for hardness, pH, alkalinity and iron bacteria. Our iron water test page covers that test.

A hardness result is not a health check. Penn State Extension says water softeners will not necessarily remove any of the more serious drinking water contamination problems, and a hardness number says nothing about bacteria, nitrate or metals. To see which tests fit your home, you can build a test plan, compare the types of water testing we cover, or read our well water testing guide for the yearly well check.

Lab test or home test strips

There are two common ways to check hardness: send a sample to a laboratory, or use a strip or kit you read at home.

A lab gives you a number. A laboratory measures the hardness of your sample with a standard method, such as the ones in the Lab methods list at the end of this section, and reports a figure you can place on the USGS classification and compare with later tests. Penn State Extension says a lab report will give hardness in one or both of two units, which the section on reading your result explains. Our directory of certified water testing labs lists state-certified labs in the states we cover, and our guide to well water testing cost shows verified lab prices. Ask the lab whether its tests include total hardness before you order.

A home strip gives you a rough read. You may see hardness strips or kits that you read by matching a color to a chart. A color you match yourself is not a measured concentration from a lab, and it gives you less to go on if you are sizing treatment or checking whether treatment works.

Free tests from a dealer. Penn State Extension notes that many water softening companies offer free hardness testing. A dealer's test can be a starting point, and Penn State advises getting a third-party evaluation from an independent lab before you buy a softener.

When to choose a lab:

• You are deciding whether to buy a water softener, or how large a unit you need.
• You want to check whether a softener you already have is working.
• You are testing a well for iron or other minerals at the same time.
• You want a result you can keep and compare with later tests.

Use a home strip as a screening step if you like, and get a lab number before you spend money on treatment.

Lab methods

• SM 2340 B
• SM 2340 C

Sources: dshs.texas.gov (source for lab methods) (opens in a new tab), dgs.virginia.gov (source for lab methods) (opens in a new tab)

How to collect a hardness sample

Hardness comes from minerals dissolved in the water that reaches your home, so a hardness sample is about the water itself. Always follow the instructions in your lab's kit, since they are written for that lab's bottle and method. The quick guide near the top of this page lists the sample bottle that a state lab's drinking-water hardness test names.

1. Check the timing. Read your lab's instructions for how soon the sample must reach it and which days it receives samples, and collect close to a shipping or drop-off time.
2. Decide what you want to know. If you have a water softener or other treatment, ask the lab whether to sample before it, after it, or both. Sampling before the softener tells you how hard the water from your well or supply line is. Sampling after it tells you whether the softener is doing its job.
3. Pick the right tap. Use a cold-water tap, unless your lab says otherwise. Penn State Extension notes that a softener does not have to treat every tap, and that some homes soften only the hot water, so check which taps your softener feeds before you choose.
4. Remove any attachments. Take off a hose or aerator attachment, unless your kit says otherwise.
5. Run the water the way your lab says. Your kit tells you whether to let the water run before you fill the bottle, and for how long.
6. Fill the bottle without rinsing it. If the bottle came with anything inside, such as a preservative, don't rinse it out, and don't let it overflow. Cap it tightly.
7. Label, pack and send. Write the date, time and tap, and whether the sample was taken before or after any treatment, then send it within the window your lab gives you.

Common mistakes to avoid

• Sampling only after a softener when you wanted to know how hard your untreated water is.
• Sampling from a hot-water tap, where water has passed through the water heater.
• Rinsing out a bottle that came with a preservative inside.
• Ordering a general panel without checking that it reports total hardness.

What your hardness level means

There is no federal drinking-water standard for hardness. EPA's national primary drinking water regulations, the legally enforceable standards for public water systems, do not list hardness. Neither does EPA's table of secondary standards, the non-mandatory guidelines for things like taste, color and odor. So there is no EPA limit to compare a hardness result with, and a hardness number on its own does not tell you your water passes or fails anything. EPA's secondary table does name hardness as one of the noticeable effects of high total dissolved solids, which has its own secondary standard; our guide to water test results explained covers that standard.

How USGS describes hardness levels. USGS gives general guidelines for classifying water by its hardness, measured as calcium carbonate:

• Soft: 0 to 60 milligrams per liter^[1]
• Moderately hard: 61 to 120 milligrams per liter^[1]
• Hard: 121 to 180 milligrams per liter^[1]
• Very hard: more than 180 milligrams per liter^[1]

These are descriptions, not limits. Other scales use slightly different steps (Penn State Extension's table, for example, adds a "slightly hard" class), so read your result against the scale your lab or source names.

Check the units. Penn State Extension says hardness is reported as milligrams per liter (the same as parts per million) of calcium carbonate, or as grains per gallon, a unit used only for hardness. It says one grain per gallon equals approximately 17 milligrams per liter^[4]. If your report gives grains per gallon, convert it before you compare it with the USGS scale.

What hardness does. USGS says scale from hard water can reduce the life of equipment, raise the cost of heating water, lower the efficiency of electric water heaters and clog pipes, and that hard water means more soap or detergent to get things clean. Penn State Extension says calcium and magnesium have no adverse health effects and are essential daily nutrients. A water test can't diagnose anything; if you have health questions, talk to a health professional.

Putting your result in context

• Soft or moderately hard. No treatment needed based on hardness. Penn State Extension says levels below 7.0 grains per gallon^[4] will probably not cause major scaling and soap film.
• Hard or very hard. Softening is a choice, not a health need. Penn State Extension calls the decision to soften a matter of personal preference, not necessity. If scale or soap film bothers you, your lab result is the starting point for comparing options.
• Before you choose any treatment. Penn State Extension notes that a softener adds sodium to the water, which it names as a potential health risk for people on low-sodium diets, and that backwashing and regeneration add load to a septic system's drainage field. MDH says iron will plug a softener. Ask about all of these with your lab report in hand, and talk to a health professional if you follow a low-sodium diet.

Hardness in a well tends to hold steady: USGS says major-ion chemistry in groundwater is relatively stable and generally does not change over time. Keep your result as a baseline. If you install a softener, a test of the softened water shows whether it works.