Private Sewage & Water Systems — Plumber (306A) Practice Questions

Free Private Sewage & Water Systems practice questions

1. 1.A septic tank's primary function is:

   • A.Complete sewage treatment
   • B.Settle solids and partially decompose organic matter through anaerobic digestion✓
   • C.Store water
   • D.Pump sewage uphill

   Why: Septic tanks separate solids (settle to bottom as sludge), allow grease to float (scum layer), and begin anaerobic decomposition. Effluent then flows to the absorption field.

2. 2.The leaching bed (absorption field) treats effluent by:

   • A.Chemical treatment
   • B.Distributing effluent through perforated pipe into soil where bacteria complete treatment✓
   • C.Evaporation only
   • D.UV treatment

   Why: Effluent percolates through gravel and into native soil where aerobic bacteria in the biomat complete treatment. Soil type and percolation rate determine field sizing.

3. 3.A holding tank differs from a septic tank in that:

   • A.It's the same thing
   • B.A holding tank has no outlet — all sewage is stored for periodic pump-out✓
   • C.It's larger
   • D.It treats the sewage completely

   Why: Holding tanks are sealed vessels with no outlet or field. All contents must be pumped and hauled to a treatment facility. Used where soil conditions don't allow a conventional septic system.

4. 4.A submersible well pump is installed:

   • A.On the ground surface
   • B.Below the water level inside the well casing✓
   • C.In the basement
   • D.On the roof

   Why: Submersible pumps are installed below the water level in the well, pushing water up. They're quieter and more efficient than jet pumps for deeper wells.

5. 5.UV water treatment kills bacteria by:

   • A.Heating the water
   • B.Exposing water to ultraviolet light that damages DNA, preventing reproduction✓
   • C.Chemical treatment
   • D.Filtering

   Why: UV systems expose water to germicidal UV-C light (254nm wavelength), damaging microorganism DNA so they can't reproduce. Effective against bacteria, viruses, and protozoa. Requires pre-filtration for clarity.

6. 6.An effluent pump in a sewage system is used when:

   • A.Always
   • B.The septic tank or pump chamber is below the leaching bed elevation and gravity flow isn't possible✓
   • C.Never
   • D.Only for greywater

   Why: Effluent pumps move clarified septic effluent from a pump chamber to an elevated leaching bed when gravity flow isn't possible due to site topography.

7. 7.A well cap must be:

   • A.Open for ventilation
   • B.Watertight and vermin-proof to prevent surface water and contamination from entering✓
   • C.Removable without tools
   • D.Made of wood

   Why: Well caps must be sanitary — sealed against surface water, insects, and vermin. A screened vent allows pressure equalization. Damaged or loose caps are the #1 cause of well contamination.

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