How to Test Water Quality in a New House Before Moving In

You’ve signed the papers, got the keys, and you’re ready to start moving boxes. The last thing on your mind is probably the water coming out of the kitchen tap — but it really should be one of the first. Most people don’t think about water quality until they’re already living in a house and something looks, smells, or tastes wrong. By then, you’ve already been drinking it for weeks. Testing the water in a new house before you move in is one of those small steps that can save you a serious headache — or worse, a serious health problem — down the road. Whether you’re buying an older home in an established neighborhood, a newer build on a well, or anything in between, the water supply situation is rarely as simple as “it’s fine, the city tests it.” Here’s how to actually do this right.

Why New-to-You Doesn’t Mean the Water Is Safe

Here’s something that catches a lot of buyers off guard: municipal water treatment does a solid job of cleaning water before it leaves the plant, but it has zero control over what happens between the treatment facility and your faucet. That gap — sometimes miles of aging infrastructure, then the private plumbing inside the house itself — is where things can go sideways. Older homes built before 1986 may have lead solder in their pipe joints, and homes built before the 1950s sometimes still have original lead service lines running from the street. When water sits in those pipes overnight, it leaches lead at levels that can far exceed the EPA’s action level of 0.015 mg/L. A city’s water quality report won’t catch that, because they’re testing at the plant or at a handful of approved sample sites — not at your specific address.

Private wells add another layer of complexity entirely. If the home you’re buying uses a well, you’re fully responsible for testing and treating that water yourself — there’s no utility doing any of it for you. Well water can contain bacteria like E. coli and coliform, naturally occurring arsenic (common in many regions of the US, including parts of the West and New England), nitrates from agricultural runoff, and a range of other contaminants that depend almost entirely on your local geology and land use. Even a well that tested clean for a previous owner can change over time as surrounding conditions shift. The point isn’t to scare you — it’s to make clear that “the house has water” and “the house has safe water” are two different statements, and only testing can tell you which one is actually true.

What Contaminants You Should Actually Test For

Not all water tests are created equal, and a basic TDS (total dissolved solids) meter from Amazon isn’t going to tell you whether your water has arsenic in it. TDS is a catch-all number that measures everything dissolved in the water — minerals, salts, metals, the whole mix — and a reading above 500 ppm is generally considered above the EPA’s secondary standard, but a low TDS reading doesn’t mean the water is safe. Some of the most dangerous contaminants, like lead or chromium-6, can be present at harmful levels while the TDS looks totally normal. What you need is a targeted list of tests based on the specific risk factors of the property. Here’s what to prioritize:

Think of this as your minimum starting checklist, adjustable based on the home’s age, location, and water source. For a city-supplied home, lead and general chemistry are the baseline. For a well, you’ll need to go further. Local health departments often publish data on regional contaminants — checking that before you order a test panel can help you focus your money on the things that are actually plausible risks in your area.

1. Lead — The single most important test for any home built before 1990. Lead has no safe level of exposure, particularly for children. Test for it using a certified lab, not a home strip test, since accurate detection requires analysis down to the parts-per-billion range.
2. Bacteria (Total Coliform and E. coli) — Essential for any home on a private well. E. coli presence indicates fecal contamination and requires immediate action. Even city-supplied homes can occasionally show bacterial issues in older distribution systems, so it’s not a bad idea to test regardless.
3. Nitrates — Critical for well water in agricultural areas. The EPA’s maximum contaminant level (MCL) is 10 mg/L, and levels above that are dangerous for infants and pregnant women. Nitrates come from fertilizer runoff and septic systems and have no taste or smell.
4. Arsenic — Naturally occurring in groundwater in many US regions, including the Southwest, Pacific Northwest, and parts of New England. The EPA’s MCL is 0.010 mg/L (10 parts per billion), but some health advocates argue even that level carries risk with long-term exposure.
5. Hardness and pH — These aren’t health threats at typical levels, but they affect how your plumbing and appliances behave. Very hard water (above 180 mg/L as calcium carbonate) can accelerate scale buildup in water heaters and pipes. pH outside the 6.5 to 8.5 range can indicate corrosive water that leaches metals from your pipes more aggressively.
6. Hexavalent Chromium (Chromium-6) — This is one that often gets overlooked in basic panels. It’s a known carcinogen found in tap water in many parts of the US, partly from industrial contamination and partly from natural geological sources. If you want to understand your exposure risk, knowing how to test for hexavalent chromium in tap water is a smart step before you move in.

Choosing the Right Testing Method for Your Situation

There’s a spectrum of testing options out there, ranging from cheap home test strips to full certified laboratory analysis, and the right choice depends on what you’re testing for and how precise you need the results to be. Home test kits are fine for a quick screening of things like pH, hardness, and chlorine — but they’re not sensitive enough to reliably detect low-level contamination of metals or organic compounds. If you’re testing for lead, arsenic, nitrates, or bacteria, you want a state-certified laboratory. The EPA maintains a list of certified labs by state, and many local health departments offer low-cost or even free testing for certain contaminants, especially bacteria and nitrates for well owners.

It’s worth noting that the accuracy of any test depends heavily on how you collect the sample. For lead testing specifically, you’ll want a “first draw” sample — water that’s been sitting in the pipes for at least six hours (typically overnight), collected before you run any taps. This gives you the worst-case scenario reading, which is what you actually want to know. For bacteria testing, the lab will send you a sterile collection vial and specific instructions to avoid contaminating the sample. Follow those instructions exactly — a false negative from a contaminated sample is the worst outcome here. The cost of a decent multi-contaminant test from a certified lab typically runs between $100 and $400 depending on what’s included, which is genuinely nothing compared to the cost of a whole-house filtration system you might install unnecessarily — or the medical bills you might rack up if you skip the test and something’s wrong.

• State-certified lab panels — Most reliable for metals, nitrates, and bacteria. Look for labs accredited under the NELAP (National Environmental Laboratory Accreditation Program) standard. Results typically take 5–10 business days.
• Mail-in test kits from reputable companies — Services like Tap Score or National Testing Laboratories let you order a kit, collect the sample at home, and mail it to their certified lab. Good option if there’s no local lab nearby. Make sure they test at a NELAP-certified facility.
• Local health department testing — Many counties offer free or subsidized testing for well owners, especially for bacteria and nitrates. Call your county health department before spending money on a private lab — you might be surprised what’s available.
• Home test strips — Acceptable for checking chlorine, pH, and general hardness as a quick sanity check. Not appropriate for detecting metals or biological contaminants at meaningful accuracy levels.
• Electronic meters (TDS, pH) — Useful for tracking trends over time once you’re in the house, but not a substitute for lab testing when you’re doing an initial assessment of an unknown water source.

Understanding Your Test Results: What the Numbers Actually Mean

Getting your results back from a lab is one thing. Understanding what those numbers mean — and what to actually do about them — is another. Lab reports can look intimidating if you haven’t seen one before. They’ll typically show the contaminant, the level detected in your sample, the EPA’s maximum contaminant level (MCL) or action level for that contaminant, and sometimes a health advisory note. The key thing to understand is the difference between an MCL and an action level. An MCL is a legally enforceable limit that public water suppliers must comply with. An action level (used for lead and copper) isn’t a maximum — it’s the point at which a utility is required to take corrective action. Detecting lead above 0.015 mg/L doesn’t mean your water is “legal” — it means there’s a problem that needs to be addressed.

The table below summarizes the key contaminants you’re likely to see on a residential water test, the regulatory benchmarks, and what a concerning result typically means in practical terms. These are the numbers worth memorizing — or at least bookmarking — before you review your report.

Contaminant	EPA Limit / Action Level	Health Concern	Common Source in Homes
Lead	Action level: 0.015 mg/L (15 ppb)	Neurological damage, especially in children; no safe level	Lead solder, lead service lines, brass fixtures
Arsenic	MCL: 0.010 mg/L (10 ppb)	Long-term cancer risk, skin and organ damage	Natural geology, industrial contamination
Nitrates	MCL: 10 mg/L	Methemoglobinemia (“blue baby” syndrome) in infants	Agricultural runoff, septic systems, fertilizers
Total Coliform Bacteria	MCL: zero detectable in any sample	Indicator of fecal contamination; risk of GI illness	Well contamination, damaged distribution pipes
pH	Secondary standard: 6.5–8.5	Corrosive water below 6.5 accelerates metal leaching	Natural geology, treatment byproducts
Total Dissolved Solids (TDS)	Secondary standard: 500 ppm	Not a direct health indicator; affects taste and scaling	Dissolved minerals, salts, metals
Copper	Action level: 1.3 mg/L	Liver and kidney damage at high levels; GI distress	Copper plumbing, especially with corrosive water
Hexavalent Chromium	No federal MCL; some states set limits	Probable carcinogen with long-term exposure	Industrial sites, natural geology

What to Do If Your Results Come Back With Problems

Finding a contaminant above safe levels in your pre-move-in test isn’t a reason to walk away from a house — at least not automatically. It’s information, and information is what you want before you sign anything or unpack anything. What you do with that information depends on the contaminant, the concentration, and the likely source. Lead, for instance, is often addressable through point-of-use filtration. A filter certified to NSF/ANSI Standard 53 for lead reduction can bring your exposure down dramatically at the tap, and it’s relatively affordable. But that’s a band-aid solution — if the home has a lead service line, you’re looking at a more serious conversation with the seller or local utility about replacement. Some cities have active lead service line replacement programs that cover at least part of the cost.

For bacterial contamination in a well, the typical first response is shock chlorination — essentially disinfecting the well with a high concentration of bleach, then flushing and retesting. It’s a well-established process that often resolves the problem, but if contamination comes back after treatment, it usually points to a structural issue with the well casing or nearby contamination source that needs a professional assessment. This is also a situation where the honest answer is: it depends. A one-time bacterial hit after a heavy rain event is a different problem than chronic contamination, and the response strategy is different too. Copper issues pair closely with pH — if you’re seeing elevated copper levels, knowing how to test for copper in drinking water and understanding the corrosivity of your water is the right starting point before you consider pipe replacement. Addressing the pH first can sometimes resolve the copper problem without touching a single pipe.

Pro-Tip: If you’re buying a home with a private well, try to negotiate a water quality contingency into your purchase agreement — this gives you the right to withdraw from the sale or request remediation if testing reveals contamination above EPA standards. Many real estate agents are familiar with this clause in rural areas, but you may need to specifically request it if you’re working with an agent who primarily handles city properties.

“Buyers almost always focus on structural inspections and overlook the water entirely — but in terms of immediate health impact, what’s coming out of the tap matters just as much as what’s holding up the roof. A thorough pre-purchase water test, particularly for lead and bacteria, takes less than a week and costs a fraction of what remediation will cost if you find a problem after closing. I tell every client: test first, negotiate second.”

Dr. Rachel Okonkwo, Environmental Health Scientist and Certified Water Quality Specialist, former consultant to the EPA’s Office of Ground Water and Drinking Water

Testing the water in a new house before you move in is one of those things that feels optional right up until it isn’t. It’s a small investment of time and money against a very large potential downside — and unlike most home inspection items, it’s something you can often use as direct leverage in purchase negotiations if something comes back wrong. Get the first-draw lead test if the house is older than 35 years. Get the full bacteria and nitrate panel if it’s on a well. Cross-check your results against the EPA benchmarks in the table above. And if something does come back elevated, don’t panic — just treat it as the starting point of a conversation, not the end of one. You now know more about that house’s water than most people ever find out about their own.

Frequently Asked Questions