WTO Water Distribution & Storage Systems 2

Question 1

What is the primary purpose of a pressure-reducing valve (PRV) in a water distribution system?

Accepted Answer

Reduce high upstream pressure to a safe downstream level

Answer

A PRV automatically reduces high upstream pressure to a lower, controlled downstream pressure to protect pipes and meters.

Question 2

Which type of water storage tank is typically used to equalize pressure in a distribution system while providing fire flow reserve?

Accepted Answer

Elevated storage tank

Answer

Elevated storage tanks use gravity to maintain system pressure and provide reserve volume for peak demand and fire protection.

Question 3

A distribution main showing a consistently low chlorine residual at the end of the line most likely indicates:

Accepted Answer

Excessive detention time causing chlorine decay

Answer

Long detention times in dead-end or low-flow mains allow chlorine to dissipate, resulting in low or zero residuals at the extremities.

Question 4

The Hazen-Williams formula is used in water distribution to calculate:

Accepted Answer

Head loss due to friction in a pipeline

Answer

The Hazen-Williams formula relates flow rate, pipe diameter, pipe roughness coefficient, and hydraulic gradient to estimate friction head loss.

Question 5

Cross-connection control programs are primarily designed to protect against:

Accepted Answer

Backflow of contaminated water into the potable supply

Answer

Cross-connection control prevents non-potable substances from entering the drinking water system through unprotected connections.

(WTO) Water Treatment Operator Certification Practice Test