Should You Cook With Filtered Water? When It Matters and When Tap Is Fine

Do You Need Filtered Water for Cooking?

Not always. If you're on city water that tastes fine and your home doesn't have lead plumbing, cooking with cold tap water is perfectly reasonable. Filtered water earns its place in the kitchen in a few specific situations: lead from older pipes and fixtures, nitrate in private well water, a chlorine taste you can pick out in your coffee or soup, and hard water that fights your dried beans and crusts your kettle.

Most lists of reasons to cook with filtered water skip the part that decides whether any of it applies to you. Two things settle it. What's actually in your water, and how much of that water ends up in the food. A pot of rice keeps nearly every drop you give it. Most of a pot of pasta water goes down the drain.

The short version: cook with cold water, don't count on boiling to clean anything up, and match any filter to a problem you've confirmed.

Which Kitchen Water Actually Ends Up in Your Food

Start here, because it sorts your cooking into high-stakes and low-stakes uses. Whatever is dissolved in the water stays with whatever absorbs it.

Formula deserves its own answer, and our guide to the best water for baby formula covers it. For everything else, the top of the table is where water quality counts most.

Two Cases Where Cooking Water Matters for Your Health

These are the situations where filtering, or at least changing how you draw your water, protects your family and doesn't just improve flavor.

Lead From Older Plumbing

Lead in tap water often comes from the plumbing itself. The EPA's basic information on lead in drinking water says lead contamination often results from corrosion of plumbing materials that belong to the homes and buildings a water system serves. Lead service lines, the pipes that connect a home to the water main, are typically the most significant source where they exist. In homes without them, the most common problem is brass or chrome-plated brass faucets and plumbing with lead solder.

Two pieces of EPA advice matter every time you fill a pot. First, use only cold water for drinking, cooking and making baby formula. Hot water is the problem, because it dissolves lead more quickly than cold water, so it's more likely to carry more of it. Filling the pasta pot from the hot tap to save a few minutes is the one kitchen shortcut worth dropping. Second, boiling water doesn't remove lead. A rolling boil deals with germs. It does nothing for the metal.

If your home might have lead in its plumbing, the EPA also suggests flushing your pipes before drinking by running the tap, taking a shower, doing laundry or running a load of dishes, and asking your water utility how long to flush in your community. If you use a filter, the EPA says to make sure it's certified to remove lead, and not to run hot water through it. Our article on why hot tap water isn't for drinking or cooking covers the water heater side of this in more detail.

Nitrate in Private Well Water

Nitrate is the case where boiling backfires. The EPA's answer to whether boiling helps with nitrate is no: boiling won't reduce nitrate levels, and it makes them worse, because some of the water evaporates but the nitrate doesn't. The same thing happens on your stovetop. A stock that simmers down for hours loses water, and the nitrate that was in that water stays in the pot.

A pitcher filter won't solve it either. An EPA Region 10 nitrate FAQ says activated carbon filters, like the ones in water pitchers, don't remove nitrates. It names two types of systems that do: reverse osmosis units and distillation units. The same FAQ explains why this matters. Too much nitrate makes it harder for red blood cells to carry oxygen, and infants may be especially vulnerable if they're fed formula mixed with well water that's high in nitrate.

This one mostly matters if you're on a private well. The EPA notes that water from private domestic wells isn't regulated by the federal government under the Safe Drinking Water Act, or by most state governments. So testing it is generally up to you. Our guide to testing well water walks through what to test for, and our nitrate explainer covers where it comes from and why it matters. For what boiling does and doesn't handle beyond these two, see whether boiling water actually purifies it.

When It's About Taste and Texture

Most of the other reasons people give for cooking with filtered water land here. They're real. They just aren't safety questions, so you can decide based on whether the difference bothers you.

Chlorine and Chloramine Taste

If your utility disinfects with chlorine or chloramine, you may be able to taste it, and you'll notice it most in things that are almost entirely water: coffee, tea, clear broth and ice. A carbon filter is the usual fix. When you shop, look at what the filter is actually certified for. NSF's overview of its filtration standards lists chlorine, taste and odor, and chloramine among the claims covered by NSF/ANSI 42, the standard for non-health-related, aesthetic effects. Chloramine is its own claim on that list, so if your utility uses it, check for that word specifically.

Our comparison of ways to remove chlorine from water goes through the options, and our coffee water guide gets into brewing specifically.

Hard Water, Dried Beans and Scaled Pots

Hard water is water high in dissolved minerals, largely calcium and magnesium, as the USGS explains. It shows up in the kitchen in two ways.

The first is dried beans. Colorado State University Extension's tips for cooking with dry beans and other pulses recommend soaking to shorten cooking time, but say to avoid hard water because it can prevent pulses from softening. So if your beans stay stubbornly firm, your water is worth ruling out. It isn't the only suspect, though. The same page notes that the drier beans get, the longer they take to cook, and very old beans may barely soften at all.

The second is scale. The USGS notes that when hard water is heated, solid deposits of calcium carbonate can form. That's the chalky white crust inside a kettle or on the bottom of a pot you boil water in often. In a pot it's mostly a cleaning chore, but the USGS points out that the same scale can reduce the life of equipment and clog pipes. If you're not sure whether your water is hard, our list of signs of hard water helps you check.

When Plain Tap Water Is Fine

Plenty of kitchen jobs don't call for filtered water at all.

• Rinsing produce. The FDA's tips for cleaning fruits and vegetables say to gently rub produce while holding it under plain running water, with no need for soap or a produce wash. Tap water that's safe to drink does that job.
• Water you pour off. Pasta and blanching water mostly go down the drain. If your water is safe to drink, the little the food absorbs isn't a reason to buy a filter.
• City water with a clean report and no taste problem. Your water supplier has to send its annual water quality report, called a Consumer Confidence Report, each year by July 1, according to the EPA. If yours shows no problems and your home doesn't have lead plumbing, cold tap water is fine for cooking. Keep in mind the report describes the water your utility delivers, not what your own pipes add. Our guide to reading your water quality report explains each column.

Match the Filter to the Problem

If you do filter your cooking water, buy for the problem you've confirmed. A filter that's excellent at one job can do nothing for another.

Because cooking water comes from the kitchen sink, that's usually where the treatment belongs. A system at the kitchen tap handles drinking and cooking water in one place. Whole-house treatment is a separate decision, driven by hardness, showers and appliances rather than by what goes into the pot.