Free practice · Water Distribution
Grade 4 Water Distribution Practice Questions
Answer each question, then reveal the correct answer and a full explanation. This is independent study material aligned to commonly tested topics, not official exam questions — exact content varies by state and exam vendor.
What is the main purpose of a cross-connection control (backflow prevention) program?
How many gallons are contained in 500 feet of 8-inch diameter pipe?
What causes water to flow through a distribution system pipe?
A pressure gauge reads 65 psi at a hydrant. What is the equivalent height of water (feet of head)?
What is the commonly required minimum horizontal separation between a new water main and a sanitary sewer main?
A water tower holds water at an elevation of 120 feet above a service connection. What is the approximate static pressure at the connection?
After a water main repair, what is the standard next step before returning the main to service?
What is the main advantage of an elevated storage tank compared to a ground-level reservoir?
Water flows through a 12-inch diameter main (cross-sectional area ≈ 0.785 ft²) at 1,000 gpm. What is the approximate velocity?
In a centrifugal pump, what component imparts velocity to the water before it is converted to pressure?
A new water main holds 45,000 gallons. Disinfecting it requires a dose of 50 mg/L. How many pounds of chlorine are needed?
Customers report reddish-brown discolored water after a main break repair in an old, unlined cast-iron main. What is the most likely cause?
A 500,000-gallon storage tank serves an area with an average daily demand of 250,000 gallons. What is the tank's turnover time?
Which backflow prevention assembly protects against both backpressure and backsiphonage, and is required for high-hazard cross-connections?
A 500-foot section of 8-inch main (cross-sectional area 0.349 ft²) needs to be unidirectionally flushed at a velocity of 2.5 ft/s to be effective. What flow rate (gpm) is needed?
Under the Revised Total Coliform Rule, what must a public water system do after a total coliform-positive routine sample?
A pump has a water horsepower output of 15 whp and draws 20 brake horsepower (bhp) as input. What is the pump's efficiency?
A pump delivers 500 gpm against a total dynamic head of 120 feet at 75% efficiency. What brake horsepower is required?
Most state drinking water regulations require distribution systems to maintain what minimum pressure under normal operating conditions?
Under the Lead and Copper Rule, what triggers a system to implement corrosion control treatment?
Want the full topic breakdown for this exam? See the Grade 4 Water Distribution exam guide, or start from the Water Distribution overview.