How Houston's Water System Works

Houston's water comes from two sources: surface water (Lake Houston, Lake Conroe, and the Trinity River via the Coastal Water Authority) and groundwater wells. The City of Houston operates one of the largest municipal water systems in the country — serving 2.2 million people through 7,500+ miles of water mains.

The system is old, massive, and under constant stress. Boil-water notices, main breaks, and pressure drops happen regularly. Understanding how the system works helps you know what is normal, what is a crisis, and who to call.

Source: City of Houston Public Works; Coastal Water Authority

Where your water comes from: Houston gets about 80% of its drinking water from surface sources (primarily Lake Houston and Lake Conroe via the Luce Bayou Interbasin Transfer) and 20% from groundwater wells. The city is actively reducing groundwater pumping to prevent land subsidence — the ground literally sinking.

Who runs what:

• City of Houston Public Works — operates the water treatment plants, distribution mains, and wastewater treatment. Responsible for water quality and delivery inside city limits.
• Harris County MUD districts — if you live outside Houston city limits but inside Harris County, your water likely comes from a Municipal Utility District (MUD). These are independent entities with their own boards.
• Coastal Water Authority — manages the raw water supply contracts and delivery from Lake Houston/Conroe to the city.

Water quality: Houston's water meets all EPA and TCEQ standards. The city publishes an annual Consumer Confidence Report with test results. Chloramine (not chlorine) is used for disinfection. If you notice taste or odor changes, it is usually from seasonal algae in the reservoirs — not harmful but noticeable.

Boil-water notices: Happen when water pressure drops below safe levels (usually during major main breaks or power outages at treatment plants). Boil all tap water for drinking, cooking, and brushing teeth until the notice is lifted. Check publicworks.houstontx.gov for active notices.

Source: City of Houston; EPA; TCEQ

Report a water problem:

• Water main break: Call 311 or 713-837-0311. If water is gushing into the street, call immediately.
• No water or low pressure: Call 311. Also check publicworks.houstontx.gov for known outages in your area.
• Discolored water: Run cold water for 5-10 minutes. If it does not clear, call 311.
• Sewer backup: Call 311 immediately. The city is responsible for the main sewer line; you are responsible for the line from your house to the main.

During a boil-water notice:

1. Bring water to a rolling boil for 2 minutes before drinking, cooking, making ice, or brushing teeth.
2. Bottled water is safe to use without boiling.
3. Bathing and showering is safe — just do not swallow the water.
4. The notice is lifted when lab tests confirm water is safe. Follow local news and publicworks.houstontx.gov.

City of Houston water:

• Report problems: 311 or 713-837-0311
• Water quality: publicworks.houstontx.gov/water-quality-report
• Billing: 713-371-1400

MUD districts (outside city limits):

• Find your MUD: tceq.texas.gov