Tap water that meets every federal standard can still carry contaminants linked to lower fertility and worse pregnancy outcomes. The gap between legal and health-protective is wide for the ones that matter most before you conceive. The EPA's legal limit for PFOA is 4 parts per trillion (ppt), but the health-based level is 0.004 ppt, a 1,000-fold difference. Atrazine's legal limit of 3 ppb sits 30 times above the Environmental Working Group health guideline of 0.1 ppb. And for lead, health scientists recognize no safe level at all. The practical fix is a reverse-osmosis or certified filter for the water you drink and cook with.
When people prepare for pregnancy, they focus on prenatal vitamins, diet, and sleep. Water rarely makes the list. Yet it's the one thing both partners consume every single day, and municipal supplies routinely carry agricultural runoff and industrial chemicals that interfere with reproductive hormones and early development. This matters for both people trying to conceive, not just the person who will carry the pregnancy. Some of these contaminants affect sperm quality; others act on the thyroid or the placenta.
Here's the honest framing before we go further. Three of the five below are true endocrine disruptors, meaning they interfere with hormone signaling. The other two are reproductive and developmental toxicants that harm fertility and pregnancy through different routes. All five share one trait: a compliance report can call your water safe while it still exceeds the health-based level.
The 5 Contaminants: Legal Limits vs. Safe Levels for TTC
Regulatory limits lag decades behind the science, because the EPA balances health risk against what utilities can feasibly afford. Independent bodies like the EWG and California's Office of Environmental Health Hazard Assessment (OEHHA) publish strictly health-based numbers instead. The table compares the two, with the CheckYourTap safe level set for the preconception and pregnancy window.
| Contaminant | EPA Legal Limit | Health-Based Guideline | CheckYourTap Safe Level (TTC/Pregnancy) |
|---|---|---|---|
| Atrazine | 3 ppb | 0.1 ppb (EWG) | 0.1 ppb (EWG) |
| PFOA | 4 ppt (2024) | 0.004 ppt (EPA HA) | 0.004 ppt (EPA health advisory) |
| Perchlorate | No federal limit | 1 ppb (EWG) | 1 ppb (EWG) |
| Nitrate | 10 mg/L (as N) | 0.14 mg/L (EWG) | 3.5 mg/L (risk-onset threshold) |
| Lead | 15 ppb action level (→10 ppb by 2027) | 0.2 ppb general-population (EWG) | No safe level (target 0) |
Three rows deserve a flag. Perchlorate has no federal drinking-water limit despite disrupting thyroid function, so "legal" here means "unregulated." Lead has no row we can honestly fill with a safe number: the 0.2 ppb figure is a general-population guideline, not a threshold below which lead becomes safe for a developing baby. And nitrate is the one row where our safe level (3.5 mg/L) sits above the EWG guideline (0.14 mg/L) rather than matching it: 3.5 mg/L is the risk-onset threshold where adverse birth outcomes start to appear in the research, while 0.14 mg/L is the stricter ideal you'd aim for if you can. We flag the risk-onset number so it stands out on a report, not because we consider it safer than EWG's target.
Citation capsule: The EPA's 2024 drinking-water limit for PFOA is 4 parts per trillion, while the agency's health advisory level, based on developmental and immune effects, is 0.004 ppt (EPA, 2024). The legal limit is therefore roughly 1,000 times higher than the health-based level, and PFOA persists in the body for years after exposure ends.
Can Atrazine in Tap Water Affect Fertility?
Atrazine is one of the most heavily applied herbicides in the United States, and its EWG health guideline of 0.1 ppb is 30 times below the 3 ppb legal limit (EWG). Because it dissolves easily in water, it washes off corn and sorghum fields into the surface water and groundwater that feed municipal systems, peaking in late spring and summer.
Atrazine acts as an endocrine disruptor, interfering with the estrogen and progesterone balance that supports ovulation, a healthy uterine lining, and early implantation. Studies of public drinking water have linked maternal atrazine exposure to preterm birth, restricted fetal growth, and lower birth weight (Rinsky et al., 2012; Chevrier et al., 2011). The proposed mechanism is placental oxidative stress, which impairs the placenta's ability to deliver oxygen and nutrients. Atrazine also crosses the placenta directly, so exposure during the earliest weeks reaches the embryo.
A point that surprises people: the wells and systems that "pass" are the quiet risk. A supply testing at 2 ppb clears the legal bar, yet it carries 20 times the EWG health guideline. During the months you're trying to conceive, that's the blind spot worth closing.
PFOA: The 'Forever Chemical' Linked to Fertility Harm
PFOA belongs to the PFAS family, and its extreme persistence is the problem: it has a biological half-life measured in years, so what you drink today keeps circulating long after. The EPA's 2024 legal limit is 4 ppt, but its health advisory level is 0.004 ppt, a 1,000-fold gap (EPA, 2024).
PFOA is associated with reduced birth weight, developmental effects, and disruption of thyroid hormone transport, according to the European Food Safety Authority's assessment (EFSA, 2020). Maternal thyroid hormones drive fetal brain development in the first trimester, before the fetal thyroid switches on, so anything that suppresses them matters early. PFOA also crosses the placenta. On the male side, higher PFOA exposure has been associated with lower sperm quality and altered reproductive hormones in men (Joensen et al., Environmental Health Perspectives, 2009), which is why both partners' exposure counts when you're trying to conceive.
Because PFOA accumulates rather than clearing, "our level is only a little over the limit" understates the risk. The body's PFOA burden reflects years of intake, not this week's glass.
Citation capsule: PFAS including PFOA cross the placenta and are associated with reduced birth weight and developmental effects, with the European Food Safety Authority setting a tolerable intake far below typical exposure levels (EFSA, 2020). PFOA's multi-year half-life means drinking-water exposure keeps circulating in the body long after intake stops.
Perchlorate: The Thyroid Disruptor With No Federal Limit
Perchlorate is the one contaminant here with no federal drinking-water limit, even though it directly disrupts the thyroid. The EWG recommends a health-based level of 1 ppb (EWG). A rocket-fuel and fireworks byproduct, it shows up in groundwater across much of the country.
The mechanism is specific and well characterized. Perchlorate competitively blocks the thyroid's uptake of iodine, the raw material for thyroid hormone (National Academies of Sciences, 2005). Lower thyroid hormone is a known contributor to irregular ovulation, reduced fertility, and, during pregnancy, impaired fetal brain development. That's why the reference dose was built around iodine-uptake inhibition rather than a downstream disease endpoint. The EPA studied perchlorate for years and ultimately declined to set a national limit, so it falls to individual states and to you to catch it.
If you already run low on thyroid hormone or have limited iodine intake, perchlorate compounds an existing vulnerability. Testing is the only way to know it's there, since it has no taste, color, or smell.
Nitrate: Farm Runoff Tied to Preterm Birth
Nitrate is the most common agricultural contaminant in American groundwater, and the fertility concern begins well below its 10 mg/L legal limit. A 2025 PLOS Water analysis of Iowa's public water found elevated risks of preterm birth and low birth weight at nitrate levels around a third of that limit, in the range of 3 to 5 mg/L (Semprini, 2025). The EWG's long-term guideline is far stricter at 0.14 mg/L.
The legal limit was set to prevent "blue baby syndrome," a blood-oxygen disorder in infants, not to protect a pregnancy. Nitrate crosses the placenta, and the developing fetus is vulnerable because fetal hemoglobin is easily oxidized and fetal enzyme defenses are still immature (OEHHA). Earlier research has also linked higher prenatal nitrate exposure to neural tube defects. We publish 3.5 mg/L as the threshold where risk starts to appear, and we treat the much lower EWG figure as the ideal you'd aim for if you can.
Nitrate is worth testing specifically if you're on a private well near cropland or livestock, where levels swing with the seasons and fertilizer schedule.
Lead: No Safe Level Before or During Pregnancy
Lead is the contaminant with no safe level, which is why our standard records zero rather than a small positive number for anyone trying to conceive or already pregnant. The EPA sets an action level of 15 ppb, dropping to 10 ppb by 2027 under the Lead and Copper Rule Improvements, but that's a treatment trigger, not a declaration of safety.
Pregnancy raises the stakes through chemistry. The body pulls calcium from bone to build the fetal skeleton, and because lead is chemically similar to calcium, that same bone remodeling releases a lifetime of stored lead back into the blood, where it crosses the placenta (EWG). Lead exposure is linked to miscarriage, preterm birth, low birth weight, and irreversible neurodevelopmental harm. It's not only a pregnancy issue, either: in men, lead is associated with reduced sperm count and quality (ATSDR, Toxicological Profile for Lead), so it can affect conception itself.
Lead usually enters at the tap, from older service lines and brass fixtures, which means your utility's source-water report can look clean while your kitchen faucet does not. That's the case for testing the water that actually comes out of your tap.
What Removes These Contaminants From Tap Water?
No single pitcher filter reliably handles all five. Standard carbon pitchers are not built to reduce PFOA, perchlorate, or nitrate to the levels above. Three technologies do the real work, and reverse osmosis is the one that covers the whole list.
- Reverse osmosis (RO) forces water through a semi-permeable membrane and removes the great majority of atrazine, PFOA, perchlorate, nitrate, and lead in one system. For preconception, an under-sink RO unit is the most reliable choice. Because RO also strips beneficial minerals, keep calcium and magnesium up through diet or prenatal vitamins. Here's what reverse osmosis actually removes.
- Certified activated carbon (solid block, NSF/ANSI 53 for VOCs and 53 or 58 for PFAS) reduces atrazine and PFOA when the cartridge has enough contact time. Gravity pitchers generally don't qualify.
- Ion exchange / anion resins capture negatively charged contaminants like PFOA, perchlorate, and nitrate; some whole-house systems pair them with catalytic carbon.
One caution that catches people off guard: don't boil tap water to make it safer for conception or pregnancy. Boiling kills microbes, but it evaporates water and concentrates lead, nitrate, and other contaminants rather than removing them.
Why We Set a Preconception-Specific Number
Most water resources publish one threshold per contaminant and hand the same figure to a healthy adult, a person trying to conceive, and a newborn. We don't. CheckYourTap sets the safe level per group, and yes, even for dogs and cats, because a body building a pregnancy clears these chemicals differently than one that isn't. We anchor each number to what the science says protects that group, not to what a treatment plant can cheaply achieve. That's a slower way to build a database, contaminant by contaminant and group by group, and we think it's the only honest one. The live personalized report covers Connecticut today, and we're expanding state by state.
Trying to conceive is exactly the window where "meets federal standards" stops being the right question. The compliance report answers a legal one. The five numbers above answer the one that matters for fertility and a healthy pregnancy, and a filter at the tap is what closes the distance between them.
This article is for general information and is not medical advice. Talk to your healthcare provider or a fertility specialist about your specific water source and any concerns.
Keep Reading
- Is Tap Water Safe During Pregnancy? The Gap Between Legal and Safe
- Arsenic in Well Water While Pregnant: Why 10 ppb Is Too High
- Reverse Osmosis: What It Actually Removes From Your Water
- Lead: sources, health effects, and safe levels
- PFOA and PFAS in drinking water
Sources: EPA PFAS Drinking Water Regulation (PFOA legal limit 4 ppt, 2024; health advisory 0.004 ppt); EWG Tap Water Database (atrazine 0.1 ppb, perchlorate 1 ppb, nitrate 0.14 mg/L, lead general-population guideline); California OEHHA Public Health Goals (nitrate and lead health basis); EFSA CONTAM Panel, 2020 (PFAS reproductive and developmental effects); EPA Lead and Copper Rule Improvements (lead action level 15 → 10 ppb); National Academies of Sciences (2005), Health Implications of Perchlorate Ingestion (thyroid iodide-uptake inhibition); Rinsky et al. (2012) and Chevrier et al. (2011) on atrazine and birth outcomes; Semprini (2025), PLOS Water, on prenatal nitrate exposure and birth outcomes.