Tap water safety is a common concern, especially during pregnancy when minimizing environmental risks is a priority. While public water systems are subject to comprehensive regulatory oversight, the quality of the water flowing from your faucet can be affected by factors closer to home, such as aging plumbing or a private well’s condition. Understanding baseline safety standards and investigating your personal water supply are important steps toward making an informed decision. Although tap water quality is generally high, certain contaminants can pose a unique risk to a developing fetus, making a personalized assessment worthwhile.
Regulatory Oversight and General Safety Standards
In the United States, the safety of public drinking water is managed under the Safe Drinking Water Act (SDWA), a federal law establishing standards for over 90 contaminants. This legislation requires public water systems to regularly monitor and treat water from its source (rivers, lakes, or groundwater) to ensure it meets health-based criteria. The regulatory framework ensures that the water delivered to a community is generally safe at the point of entry into the distribution system.
The water’s safety can change after it leaves the treatment plant and travels through the pipe network. Municipal systems manage the main distribution lines, but the pipes leading into and within an individual home are the homeowner’s responsibility. This distinction is important because while source water is heavily regulated, the final quality at the tap can be compromised by a home’s specific infrastructure.
The SDWA does not regulate private well water, which is used by millions of households. Owners of private wells must assume responsibility for their water quality, as no federal or state agency provides routine testing or oversight for these sources. Therefore, general safety standards applied to public water do not extend to private supplies, requiring a different approach to risk assessment.
Critical Water Contaminants to Avoid
Contaminants in drinking water are of particular concern during pregnancy due to their potential to affect fetal development.
Lead
Lead is a recognized threat because it can cross the placenta starting around the twelfth week of gestation. This heavy metal is a potent neurotoxin released into water from old lead service lines, lead solder, or brass fixtures. Exposure to lead during pregnancy is associated with increased risks of miscarriage, preterm birth, and low birth weight. It can also harm the baby’s developing brain and nervous system.
Nitrates
Nitrates require attention, especially in agricultural areas where fertilizer runoff contaminates groundwater. When ingested, nitrates convert into nitrites, which interfere with the blood’s ability to carry oxygen. Studies have linked nitrate exposure, even below the federal standard of 10 milligrams per liter, to adverse outcomes like preterm birth and low birth weight. Pregnant people should aim for levels below 5 milligrams per liter due to emerging evidence of risk at lower concentrations.
Pathogens and Disinfection Byproducts
Pathogens, such as E. coli or Cryptosporidium, are typically managed through municipal disinfection. They become a concern following infrastructure failure or in poorly maintained private wells. Exposure to these biological contaminants can cause gastrointestinal illness, which may increase the likelihood of preterm delivery.
Trihalomethanes (THMs) are another group of contaminants. They are byproducts formed when chlorine used for disinfection reacts with natural organic matter in the water. Some studies suggest that higher exposure to THMs may be linked to an increased risk of congenital anomalies and retarded fetal growth.
How to Assess the Safety of Your Home Water Supply
Determining the quality of the water flowing from your tap requires a localized and proactive approach.
Public Water Systems
For those receiving public water, the most direct source of information is the annual Consumer Confidence Report (CCR), which the utility must provide. This report details the water’s source, detected contaminant levels, and regulatory compliance. The CCR is important for reviewing contaminants like nitrates and THMs, which are monitored throughout the distribution system.
The CCR does not reflect the condition of your home’s plumbing, which is the primary source of lead contamination. If you live in a home built before 1986 (when lead pipes were common) or before 1988 (when lead solder was banned), a professional water test specifically for lead is recommended. This test should be conducted by a certified laboratory, collecting a sample after the water has sat in the pipes for several hours to capture the highest potential lead concentration.
Private Wells
For those using a private well, the responsibility for testing falls entirely to the homeowner, as there is no regulatory oversight. Well water should be tested at least once a year, or more frequently if the taste, odor, or color changes. A comprehensive well test should include coliform bacteria, pH, and, critically for pregnant people, nitrates. A state-certified lab should perform this testing, as the results are more accurate and detailed than simple at-home kits.
Treatment Options and Safe Water Alternatives
If testing reveals contaminant levels of concern, or if you prefer a precautionary approach, several effective treatment options are available. Point-of-use filtration systems, which treat water at a single tap, are often the most practical solution for drinking and cooking water.
Filtration Systems
Activated carbon filters are effective at removing chlorine and THMs, significantly reducing lead, and improving taste. For a broader range of contaminants, including nitrates, reverse osmosis (RO) systems are comprehensive options. RO systems force water through a semipermeable membrane, removing up to 99% of substances like heavy metals, nitrates, and dissolved solids. When selecting a system, choose a filter certified to reduce the specific contaminants of concern and follow the manufacturer’s schedule for filter replacement to maintain effectiveness.
Alternatives to Filtration
Boiling water is effective only for killing biological pathogens like bacteria and viruses, useful during a boil water advisory. However, boiling does not remove chemical contaminants; it causes them to concentrate as the water evaporates. Therefore, boiling is an unsafe alternative for reducing chemical threats like lead or nitrates. Bottled water may be necessary if tap water has high contaminant levels that cannot be filtered. However, it is not inherently safer than regulated tap water and carries trade-offs such as cost, plastic waste, and potential microplastic exposure.