LAS VEGAS (CITY OF)

What this violation means

Total coliform bacteria are themselves usually harmless, but their presence signals that the water distribution system has a vulnerability — typically a cracked pipe, loss of pressure, or back-siphonage — that could allow disease-causing pathogens to enter. Repeated coliform-positive samples trigger mandatory utility investigation.

Recommended precautions

• →If your utility issues a boil-water advisory, boil all drinking and cooking water for at least one minute.
• →Use bottled water until the advisory is lifted.
• →Ice from icemakers and beverages made before the advisory should be discarded.
• →UV light and chlorination both kill coliform bacteria — most home filters do not.

What this violation means

E. coli detection is an EPA Tier 1 acute violation, requiring same-day public notification. It confirms that fecal matter has entered the drinking water supply, posing immediate health risks — particularly to children, the elderly, and immunocompromised individuals.

Recommended precautions

• →Do not drink the water until the utility has lifted the advisory.
• →Boil water for at least one minute (three minutes at elevations above 6,500 ft).
• →Disinfect dishes and surfaces that touched contaminated water.
• →Seek medical attention if you develop bloody diarrhea or persistent vomiting.

What this violation means

Total Trihalomethanes (TTHMs) form when chlorine reacts with naturally occurring organic matter — leaves, soil, algae — in source water. They are among the most commonly reported violations because utilities pulling from surface water (rivers, lakes, reservoirs) struggle to balance disinfection with byproduct formation. Long-term exposure has been linked to bladder cancer and adverse pregnancy outcomes.

Recommended precautions

• →Activated carbon filters (pitcher, faucet, or under-sink) effectively reduce TTHMs.
• →Letting water sit uncovered allows TTHMs to off-gas — leave a pitcher in the fridge for several hours.
• →Shower with the bathroom fan on; TTHMs can volatilize into the air during hot showers.
• →Boiling reduces TTHMs through volatilization, but only after extended boiling.

What this violation means

Haloacetic Acids (HAA5) are the second major group of disinfection byproducts after TTHMs. They form by the same mechanism — chlorine reacting with organic matter — and pose similar long-term cancer risks. Utilities are required to test quarterly at distribution-system locations to track HAA5 levels.

Recommended precautions

• →Activated carbon filtration removes most HAA5.
• →Reverse osmosis is highly effective.
• →Unlike TTHMs, HAA5 do not significantly off-gas. Use treatment rather than aeration.
• →Long-term ingestion is the primary concern, not short-term skin contact.

What this violation means

Total coliform bacteria are themselves usually harmless, but their presence signals that the water distribution system has a vulnerability — typically a cracked pipe, loss of pressure, or back-siphonage — that could allow disease-causing pathogens to enter. Repeated coliform-positive samples trigger mandatory utility investigation.

Recommended precautions

• →If your utility issues a boil-water advisory, boil all drinking and cooking water for at least one minute.
• →Use bottled water until the advisory is lifted.
• →Ice from icemakers and beverages made before the advisory should be discarded.
• →UV light and chlorination both kill coliform bacteria — most home filters do not.