Main water shutoff valve — location, operation, and condition

Valve must turn fully and hold. Gate valves over 15 years old are prone to failure under pressure. Ball valves preferred.

Water pressure at main supply (target: 45–80 PSI)

Pressure below 40 PSI causes weak flow. Above 80 PSI accelerates wear on fixtures, appliances, and supply lines. A pressure reducing valve (PRV) is required if pressure exceeds 80 PSI.

Pressure reducing valve (PRV) — presence, setting, and condition

PRV should be set between 50–65 PSI. Diaphragm PRVs have a 10–15 year service life. Failing PRVs cause pressure fluctuation and can allow pressure spikes that damage appliances.

Water meter condition and accessibility

Meter should be accessible and readable. Unusually high usage on the meter with no explanation indicates a hidden leak.

Supply line material identification (copper, PEX, CPVC, galvanized, polybutylene)

Polybutylene (gray plastic, installed 1978–1995) is prone to catastrophic failure and should be replaced. Galvanized steel corrodes from the inside, reducing flow and contaminating water with rust.

Visible supply line condition — corrosion, pinhole leaks, joint integrity

Green staining on copper indicates active corrosion. White or blue-white deposits indicate mineral buildup at joints. Any active seepage requires immediate attention.

Individual fixture shutoff valves — presence and operation

Every fixture (toilet, sink, dishwasher, washing machine) should have a dedicated shutoff valve. Valves that haven't been operated in years may be seized and fail when needed most.

Expansion tank — presence and condition (required on closed systems)

Required by code when a PRV, backflow preventer, or check valve creates a closed system. Without an expansion tank, thermal expansion from the water heater pressurizes the entire system, causing premature fixture and appliance failure.

Backflow preventer — presence and condition

Required on irrigation systems, hose bibs, and any cross-connection point. Prevents contaminated water from flowing back into the potable supply.

Hose bibs — condition, backflow protection, and winterization

Exterior hose bibs should be frost-free type in Maryland's climate. Standard hose bibs without vacuum breakers are a code violation and contamination risk.