Drinking Water Safety & Quality

How Tap Water Is Regulated

“The Safe Drinking Water Act (SDWA) was originally passed by Congress in 1974 to protect public health by regulating the nation’s public drinking water supply.” EPA sets the national standards, and “US EPA, states, and water systems then work together to make sure that these standards are met.”⁠^[1]

In New York, “the Department of Health in cooperation with county health departments, regulates the operation, design and quality of public water supplies and commercial bottled water suppliers.”⁠^[2] The department adds that “Public water systems in New York must monitor for more than 100 different contaminants on a regular schedule, including PFOA, PFOS and 1,4-dioxane.”⁠^[3]

New York’s environmental and health departments describe how public water systems work:

“Public water systems draw water from well-defined sources, treat the water to meet all federal and state drinking water standards, distribute the water to the public through a system of water mains and storage tanks, and continuously monitor water quality to ensure the provision of potable water.”

They add: “If standards are not being met, the public water suppliers are required to notify customers and take actions to come into compliance.”⁠^[4]

Where Long Island’s Water Comes From

The U.S. Geological Survey states that “Groundwater is the sole source of freshwater supply in Nassau and Suffolk Counties on Long Island.”⁠^[5] The Nassau County Department of Health explains that “Nassau County gets all its drinking water from the water stored in the porous soil beneath Long Island,” and that “Nassau County uses three major aquifers for its drinking water.”⁠^[6]

Your Annual Water Quality Report

“EPA requires community water systems to deliver a Consumer Confidence Report, also known as an annual drinking water quality report, to their customers.” EPA adds: “Reports must be sent by your water supplier each year by July 1.”⁠^[7]

According to EPA, each report includes, among other things:⁠^[7]

• “The lake, river, aquifer, or other source of the drinking water”
• “The regulated contaminant found in local drinking water”
• “Educational information on nitrate, arsenic, or lead in areas where these contaminants may be a concern”

To find yours, the New York State Department of Health lets you “Find and map a large public water system closest to you and view its Annual Drinking Water Quality Report.”⁠^[2] New York’s environmental and health departments also suggest you “contact your water supplier to view the latest results.”⁠^[4]

Cloudy, Discolored or Odd-Smelling Water

The Suffolk County Water Authority (SCWA) publishes a step-by-step troubleshooting guide. If your water comes from another supplier, check its guidance too.

Cloudy or milky water

SCWA says “Milky or cloudy water is almost always caused by harmless trapped air. Changes in temperature or pressure in the main create micro-bubbles that make the water look white.” Its test: fill a clear glass and watch it for 2 minutes. “If it clears from the bottom upward: It is just trapped air.”⁠^[10]

Brown, rusty or discolored water

First check whether only the hot water is affected. SCWA explains: “If only the hot water is discolored: The issue is inside your water heater (often sediment buildup). You will need to contact a plumber to flush your water heater tank.”⁠^[10]

If the cold water is discolored, SCWA’s advice is to go to a “faucet without a screen or aerator (such as a bathtub or outdoor spigot) and run the cold water only on full blast.” It explains that “SCWA performs routine flushing of water mains, and occasionally natural sediment can enter a service line. Running your cold water flushes it safely out.”⁠^[10]

Minerals can also color water. EPA’s secondary standards list noticeable effects above 0.3 mg/L of iron (“rusty color; sediment; metallic taste; reddish or orange staining”) and above 0.05 mg/L of manganese (“black to brown color; black staining; bitter metallic taste”).⁠^[11] These are guidelines for aesthetics, and EPA states that “These contaminants are not considered to present a risk to human health at the SMCL.”⁠^[11]

Unusual smells and tastes

EPA’s secondary standards include odor, describing a “‘rotten-egg’, musty or chemical smell” as the noticeable effect, and note that “Odor and taste are useful indicators of water quality even though odor-free water is not necessarily safe to drink.”⁠^[11] If you notice a chlorine taste, EPA describes chlorine as a “Water additive used to control microbes” and sets a maximum residual disinfectant level of 4.0 mg/L.⁠^[12]

Hard Water

“In scientific terms, water hardness is generally the amount of dissolved calcium and magnesium in water,” according to the U.S. Geological Survey, and “Hardness is a property of water that is not a health concern, but it can be a nuisance.”⁠^[13] USGS uses these ranges, measured as calcium carbonate:⁠^[13]

USGS notes that “When using hard water, more soap or detergent is needed to get things clean” and that “When hard water is heated, such as in a home water heater, solid deposits of calcium carbonate can form.”⁠^[13] The CDC explains that “Water softeners remove minerals, primarily calcium and magnesium, from water.”⁠^[14] A water test can show how hard your own water is.

Recent Rule Changes

• Lead pipes (October 2024): EPA “issued a final rule requiring drinking water systems across the country to identify and replace lead pipes within 10 years.”⁠^[15] See lead in drinking water.
• PFAS (April 2024 and May 2026): EPA finalized limits of 4.0 parts per trillion for PFOA and PFOS in April 2024,⁠^[9] and in May 2026 proposed letting water systems request two more years, to 2031, to comply.⁠^[16] See our PFAS guide.
• 1,4-Dioxane in household products (December 2025): New York’s waivers for manufacturers ended on December 30, 2025, after which “all products will need to comply with the limits.”⁠^[17] See our 1,4-dioxane guide.
• Water quality reports (2027): larger systems will send reports twice per year, as described above.⁠^[8]

Private Wells

None of the public water rules above covers a private well. EPA says “Private well owners are responsible for delivering safe drinking water to their households,”⁠^[18] and the New York State Department of Health advises that “Private well owners should test their tap water at least once a year for bacteria and every three to five years for other contaminants.”⁠^[19] Read more in our private well guide.