Download Mississippi State Department of Health (MSDH) Onsite Wastewater Installer/Contractor cert and more Exams Water and Wastewater Engineering in PDF only on Docsity!
Mississippi State Department of Health (MSDH) Onsite
Wastewater Installer/Contractor certification Exam Questions
And Correct Answers Plus Rationales 2025.
- What is the primary function of a septic tank in an onsite wastewater system? A) Aerate wastewater B) Store sludge permanently C) Filter solids from drinking water D) Separate solids and scum from liquid wastewater A septic tank settles solids and retains scum, allowing clarified effluent to flow to the drainfield.
- What is the minimum setback distance from a private well to a conventional septic system in Mississippi? A) 50 feet B) 25 feet C) 10 feet D) 100 feet MSDH requires a minimum 100-foot separation from a private water well to reduce groundwater contamination risks.
- When must a licensed installer submit an “as-built” drawing to MSDH? A) Only when requested by the property owner
B) After every installation C) Only for commercial systems D) It is never required As-built drawings show the exact placement of the system and are mandatory for recordkeeping.
- Which soil texture is least suitable for a conventional subsurface wastewater system? A) Sandy loam B) Loamy sand C) Clay D) Fine sand Clay soils have poor permeability, leading to ponding and system failure.
- What is the purpose of a distribution box? A) Remove pathogens B) Evenly distribute effluent to drainfield trenches C) Store effluent D) Add chemicals to the effluent A distribution box helps equalize effluent flow among multiple trenches.
- Which MSDH regulation covers individual onsite wastewater disposal systems? A) MSDH Chapter 20 B) MSDH 15-Section 5 C) MSDH Public Health Law 101
10.Which material is commonly used for lateral lines in a conventional drainfield? A) Copper pipe B) Perforated PVC pipe C) Cast iron pipe D) Flexible rubber hose Perforated PVC pipe allows effluent to seep evenly into the soil. 11.Which type of onsite system uses aerobic treatment to improve effluent quality? A) Holding tank B) Septic tank only C) Aerobic treatment unit (ATU) D) Lagoon An ATU uses oxygen to help bacteria break down waste more efficiently. 12.A properly functioning drainfield relies on what type of soil property? A) Impermeable clay B) High water table C) Adequate percolation rate D) Compacted soil layers Good percolation allows effluent to filter through soil for final treatment. 13.How is trench depth determined for a drainfield? A) Based on the installer’s preference B) Arbitrarily set at 5 feet C) Based on percolation test results and soil evaluation
D) Always above ground Trench depth must ensure proper filtration and separation from groundwater. 14.Who is legally responsible for ensuring the installation meets MSDH standards? A) Homeowner only B) Manufacturer C) Licensed installer/contractor D) Realtor The licensed installer must comply with MSDH requirements. 15.When backfilling a trench, what material should be placed over the drainfield pipe? A) Concrete B) Topsoil only C) Washed gravel D) Sandbags Gravel promotes drainage and helps distribute effluent. 16.What is a “mound system” designed to overcome? A) Poor quality effluent B) Shallow soils with high water tables C) Heavy equipment loads D) Low organic content Mound systems raise the absorption area above restrictive conditions.
D) Placing plastic liners Compaction reduces soil’s ability to absorb and treat effluent. 21.Which household activity most commonly overloads a septic system? A) Turning off faucets B) Running multiple loads of laundry back-to-back C) Using low-flow fixtures D) Taking short showers Doing too much laundry at once can flood the system with excess water. 22.A malfunctioning septic system may show which sign? A) Brown grass over drainfield B) Foul odor inside the house C) Lush, wet areas over the drainfield D) High electricity bill Soggy areas and bright green grass indicate effluent surfacing. 23.Who can perform soil evaluations for new installations? A) Anyone B) The homeowner’s neighbor C) Certified soil evaluator or licensed engineer D) The realtor MSDH requires a trained professional for soil evaluations. 24.How does a pump tank benefit an onsite system? A) Stores solids B) Removes odors C) Pumps effluent to higher elevation drainfields
D) Filters solids Pump tanks lift effluent when gravity flow is insufficient. 25.What is the purpose of effluent filters? A) Aerate the effluent B) Chlorinate the effluent C) Trap solids before they enter the drainfield D) Store sludge Effluent filters reduce solids from clogging the drainfield. 26.What is required before installing an onsite system in Mississippi? A) Verbal approval from the neighbor B) Self-inspection by the installer C) MSDH permit D) Homeowner’s insurance It is illegal to install without a valid permit. 27.When must a malfunctioning system be repaired? A) Only during dry months B) When the homeowner sells the house C) Immediately upon discovery D) After 5 years Prompt repairs protect public health and the environment. 28.Which maintenance practice extends system life? A) Flushing wipes B) Conserving water usage C) Adding motor oil
D) Call the electric company System drawings show the original location for safe access. 33.Which site condition may require an alternative system? A) Deep, permeable soils B) Low rainfall C) Good percolation D) High groundwater table High water tables limit treatment below the trench. 34.What is the first step when sizing a system? A) Build the tank B) Install the pump C) Determine daily wastewater flow D) Plant grass Flow estimates help size the tank and drainfield. 35.What protects the drainfield from soil erosion? A) Bare soil B) Heavy equipment C) Concrete slab D) Grass cover Grass helps prevent erosion and provides evapotranspiration. 36.Who enforces onsite wastewater regulations in Mississippi? A) State police B) Mississippi State Department of Health C) County clerk
D) City mayor MSDH regulates system design, installation, and maintenance. 37.What happens if an installer works without a license? A) Nothing B) Gets a bonus C) May face penalties or fines D) Gets free supplies Unlicensed work violates state law. 38.How can installers protect groundwater? A) Discharge effluent to ditches B) Install tanks in wetlands C) Follow MSDH design and setback rules D) Dump solids behind the house Proper siting and design keep contamination away from wells. 39.What is the minimum size for a residential septic tank? A) 100 gallons B) 250 gallons C) 500 gallons D) 1,000 gallons MSDH requires at least 1,000 gallons for typical homes. 40.What tool measures soil permeability? A) Thermometer B) Altimeter C) Percolation test kit
D) 20+ years With proper care, systems can function for decades. 45.What is the impact of installing a system in the rain? A) No impact B) Helps settle soil C) Causes soil smearing and compaction D) Speeds up percolation Wet conditions can damage soil structure, reducing effectiveness. 46.Which test shows the seasonal high water table? A) Soil temperature test B) Soil boring and color analysis C) Water pressure test D) Electric circuit test Soil mottling and colors indicate historical saturation levels. 47.What does the term “failing system” mean? A) The grass is dying B) The system is discharging untreated effluent to the surface C) It is too old D) It has an odor Untreated surfacing effluent is a public health hazard. 48.What type of permit is needed for a repair? A) Electrical permit B) Fire permit C) Building permit only
D) MSDH onsite repair permit MSDH must approve repairs to ensure code compliance. 49.Who should inspect a system annually for problems? A) Realtor B) Neighbor C) Licensed professional or knowledgeable homeowner D) Police officer Regular inspections catch issues early. 50.Which practice protects public health? A) Overflowing tanks B) Surfacing effluent C) Using a system without a permit D) Proper design, installation, and maintenance Following regulations keeps waste out of drinking water and the environment. 51.What is the effect of heavy rainfall on a drainfield? A) It speeds up percolation B) It improves bacterial action C) It may saturate the soil and cause failure D) It flushes the tank Excess water can prevent effluent from properly filtering, leading to surfacing and backups.
D) Grass or vegetative cover Vegetation insulates the soil, reducing the chance of freezing pipes. 56.What does the term “scum layer” refer to? A) The cleanest wastewater B) Solids in the drainfield C) Discharge pipe D) Floating solids and grease in the tank The scum layer floats on top and must be kept in the tank to avoid clogging the field. 57.What is the main purpose of baffled tank inlets and outlets? A) To remove sludge B) To prevent solids from leaving the tank C) To aerate the tank D) To pump water uphill Baffles keep solids and scum trapped inside the tank. 58.When are effluent pumps used? A) Only in cities B) To add air C) When gravity flow is not possible D) To pump solids Pumps lift effluent to higher elevation drainfields. 59.What does “hydraulic overloading” mean? A) Proper tank sizing B) Too much wastewater entering the system at once
C) Installing larger pipes D) Low water use Hydraulic overload can flood the drainfield, causing backups. 60.What happens if you build structures over a drainfield? A) It works better B) The soil percolates faster C) The system can fail due to compaction and lack of oxygen D) It reduces maintenance Structures compact soil and block oxygen, harming treatment. 61.Which document must be kept on file after system installation? A) Grocery list B) Electricity bill C) Fence permit D) MSDH permit and final approval The permit and as-built are needed for inspections and future repairs. 62.Which type of pipe is NOT recommended for drainfield laterals? A) Perforated PVC B) Solid, non-perforated pipe C) Gravelless chambers D) Pipe with holes on bottom Solid pipe doesn’t allow effluent to disperse into the soil. 63.What role does a curtain drain play? A) Holds effluent B) Diverts groundwater away from the drainfield
B) A pipe or riser to view tank or drainfield conditions C) A drain trap D) A vent Ports allow easy monitoring for maintenance. 68.What is the “invert” in a pipe? A) The cap B) The external diameter C) The lowest inside point of the pipe D) The pump connection The invert controls the flow level in gravity systems. 69.Which soil horizon is best for treatment? A) Solid bedrock B) Hardpan C) Clay lens D) Loamy sand or sandy loam These soils provide good filtration and percolation. 70.What is a “grease trap” used for? A) Pumping water uphill B) Aerating wastewater C) Catching solids D) Capturing grease before it enters the septic system Grease traps prevent clogs and protect tank bacteria. 71.Which condition often indicates system failure? A) Low water use
B) Dead grass C) Sewage surfacing above the drainfield D) Dry trenches Surface effluent means the soil is overloaded or clogged. 72.How often must a licensed installer renew their license? A) Never B) Every 10 years C) As required by MSDH (typically annually) D) Monthly Licenses must be kept current to stay in compliance. 73.How deep should the gravel layer be under drainfield pipe? A) 1 inch B) 2 inches C) 4 inches D) At least 6 inches A proper gravel bed ensures good drainage. 74.When must the property owner sign off on the installation? A) After final grading B) When they sell the house C) When they receive the final approval D) Only for commercial sites Owner acknowledgment is part of the MSDH approval process. 75.What is a “dose” in wastewater treatment? A) A chemical additive
