Drainfield Do’s and Don’ts

Do These Things

• Know where your drainfield and replacement area are located. When you know where it is located, it is easier to protect. For more information call Lilly’s Septic at 425-432-3084   253-639-3606   360-825-4809.
• Keep heavy equipment off your drainfield. Cars and heavy equipment should not park or drive over the drainfield; doing so can crack pipes. Create a barrier if accessible to cars, livestock, or heavy equipment.
• Keep water usage to a minimum. Drainfields do not have an unlimited capacity. When there is more water than it can absorb, the system is unable to drain and filter effluent before it reaches groundwater.
• Divert water away from the drainfield. Water runoff from roofs and drainage ditches can saturate the soil. Drainfields are most efficient when the soil beneath the drainfield is not saturated.
• Keep trees and shrubs at least 30 feet away from the drainfield. (NOTE: Some soil conditions may require that plantings be kept an even greater distance from the drainfield.) Trees and shrubs generally have extensive root systems that seek out and grow into wet areas, such as drainfields. This can lead to clogged and damaged drain lines. For more information, see Landscape Your Drainfield.
• Plant only grass or shallow-rooted plants over the drainfield. This will prevent soil erosion.
• Protect your replacement area. It may be the only area with acceptable soil conditions in case you need to replace, repair, or add on to the drainfield. All of the above suggestions apply to the replacement area as well.

Don’t Do These Things

• Don’t build over your drainfield. This includes patios, carports, and other structures. You may damage the drainfield.
• Don’t pave over the drainfield. Drainfields need air to function properly. Oxygen is needed by bacteria to break down and treat sewage.
• Don’t dig in your drainfield. Damage to the pipes can occur.
• Keep large animals and livestock off the drainfield. Soil compaction prevents oxygen from getting into the soil and prevents water from flowing away from the drainfield.
• Don’t use landscaping plastic over the drainfield. Air is necessary for the drainfield to function efficiently.
• Don’t plant a vegetable garden over a drainfield. You risk the possibility of food contamination.
• Don’t install an irrigation system in the drainfield. Neither should the irrigation system drain toward the drainfield.

The Drainfield

How It Works

The drainfield is a network of perforated pipes (or “laterals”) laid in gravel-filled trenches or beds. After solids settle in the septic tank, the liquid wastewater (or effluent) is discharged, either by gravity or pressure, to an absorption field, also known as a drainfield or leachfield. NOTE: In most gravity systems the wastewater first flows into a distribution box (d-box) or tee, which then disburses the effluent equally among the trenches in the drainfield, which is where the final treatment takes place.

Effluent trickles out of the pipes, through the gravel layer, and into the soil where further treatment occurs. The soil filters the wastewater as it passes (or “percolates) through the pore spaces and the soil microbes treat it before it eventually enters the groundwater. These processes work best where the soil is somewhat dry, permeable, and contains plenty of oxygen for several feet below the drainfield.

The drainfield is generally located in a stretch of lawn in the back or side yard of a property. The size and type of drainfield depends on the estimated daily wastewater flow and local soil conditions.

The Soil

The soil below the drainfield provides the final treatment and disposal of the septic tank effluent. After the wastewater has passed into the soil, organisms in the soil treat the effluent before it percolates downward and outward, eventually entering ground or surface water. The type of soil also impacts the effectiveness of the drainfield; for instance, clay soils may be too tight to allow much wastewater to pass through and gravelly soil may be too coarse to provide much treatment.

Replacement (Reserve) Area

Every new home or building served by a septic system is required to have a designated replacement or reserve area. This is a designated area suitable for a new drainfield and must be treated in the same manner as your existing drainfield. (A reserve area should have been designated as part of the permit process for any sewage system installed since 1980.)

Once a septic system has failed, it is too late to solve the problem by pumping your tank. A new drainfield will have to be installed at a different location. This is why it is important to know where the replacement area is located and how to protect it (see “Drainfield Do’s and Don’ts” for replacement area care).

Is Your Septic System Failing? … What are the Warning Signs

If you notice any of the following signs of a potential failure or if you suspect your septic system may be having problems, contact  for further diagnostics. Should your Septic fail contact Lilly’s Septic Service at 253-639-3606  425-432-3084  360-825-4809

Odors, surfacing sewage, or wet spots in the drainfield area.

• Plumbing or septic tank backups (often a black liquid with a disagreeable odor).
• Slow draining fixtures.
• Gurgling sounds in the plumbing system.
• If you have a well and tests show the presence of coliform (bacteria) or nitrates, your drainfield may be failing.
• Standing liquid over the drainfield, even during dry weather. This may indicate an excessive amount of effluent is moving up through the soil, instead of downward.

Inspecting your Septic Tank

The Stick Test

Septic tanks are mainly settling chambers. They allow time for solids and scum to separate out from wastewater, so clear liquid can safely go to the drainfield. Over time, the scum and sludge layers get thicker, leaving less space and time for the wastewater to settle before passing to the drainfield.

For every gallon entering the tank, one gallon is pushed out into the drainfield. So it is important to keep the level of scum and sludge from building up and nearing the inlet or outlet baffles, where the scum or sludge could plug them up or be carried out to the drainfield.

Septic tanks should be checked for buildup every 1 to 3 years until you can get on a predictable pumping schedule. Most septic tanks need pumping every 3 to 5 years. How often depends on the size of the tank, the number of people in the household, and the amount and type of solids entering the tank.

You can hire a professional or inspect your septic tank yourself. The “stick test” procedure will guide you through the steps of measuring the amount of scum and sludge in the tank, discovering the working capacity of the tank, and determining whether the tank needs pumping. A more complete inspection includes inspecting the condition of the baffles and the pipe seals into and out of the tank.

What You Need to Do the Stick Test

• two 10-foot PVC pipes*
• four end caps*
• one 90° elbow*
• PVC cement (blue cement used in rain and wet)
• two adapters, SxMPT, threaded*
• one coupler, threaded*
• two feet of white rag or old towel or old gym sock
• string or duct tape
• pencil or waterproof marker
• rubber gloves
• disinfecting solution made of 1/4 cup bleach per gallon of water in a bucket
• plastic bag for disposal of towel, rag/sock, gloves
  
  *all PVC materials are 1/2-inch Schedule 40 PVC plastic

The scum stick at right is 6 feet long with a 6-inch leg. The sludge stick is two 5-foot sections screwed together. (NOTE: Scum and sludge sticks can be any length up to 10 feet.)

Step 1 — Uncover the Tank

First uncover and remove the first manhole cover. Some systems have “risers” that make this job easier by bringing the tank lids up to the ground surface. (We encourage you to have risers installed so you won’t need to dig down each time you inspect.)

The diagram at left shows the top of the two most common septic tank configurations. The upper figure is found on newer tanks and the bottom one is usually found on older septic tanks. In most cases, the hole to the left is the first compartment, the hole to the right is the second compartment, and the rectangular cover is to the crossover baffle. (Some tanks, 25 years or older, may have only one compartment that is round, oval, or square.)

Step 2 — Measure the Scum Level

This procedure determines the thickness of the scum level (SC).

1. To make the scum stick — Cut one of the 10-foot PVC pipes to 6 feet. Glue a 90° elbow to one end. Cut a 6-inch piece of PVC pipe and glue to elbow. Place end caps on open ends.
2. Lay a board or stick across the top of the hole, manhole, or riser.
3. Place the scum stick down the manhole of the first compartment of the tank until it rests on top of the scum layer  and mark the scum stick where it crosses the reference point .
4. Work the stick through the scum layer, leading with the elbow end. Push straight through the scum layer, turn the stick 90°, pull up on the stick until you feel the bottom of the scum layer.
5. Mark the scum stick where it crosses the reference point .
6. Remove the scum stick and measure the distance between the two marks. This is the thickness of the scum layer (SC).

Step 3 — Measure the Sludge Level

This procedure determines the thickness of the sludge level (SL).

1. To make the sludge stick — cut the other 10-foot PVC pipe into two 5-foot sections. Glue an adapter to each stick. Screw the coupler into one of the adapters. Connect the two sections to make a 10-foot stick.
2. Tightly wrap two feet of a white rag or old towel around the bottom of the stick. Fasten it with tape or string.
3. Make hole in scum — do not stain the sludge stick with scum.
4. Carefully lower stick through the hole in scum in first compartment until it rests on top of the liquid layer. Mark the stick where it crosses the opening of the manhole or riser
5. Lower the stick to the bottom of the tank. Hold the stick in the tank for at least five minutes to allow sludge particles to adhere to the towel.
6. Mark the sludge stick where it crosses the board .  The distance between the two marks  is the working depth of the tank (WD).
7. Carefully remove the stick. There should be a distinct dark stain on the rag. Measure the height of the stain. This is the depth of the sludge layer (SL).

WHEN TO PUMP Pump the tank when the sludge depth, plus the scum depth, is greater than one-third of the working depth of the tank: (a) SC _____ inches + SL _____ inches = _____ (b) WD _____ divided by 3 = _____ If (a) is greater than (b), the tank needs pumping. For example, if SC = 10, SL = 8, and WD is 48″: 10 + 8 = 18 inches and 48/3 = 16 inches… 18 is greater than 16, so the tank needs pumping.

Step 4 — Inspecting the Baffles

Remove the covers over the inlet, outlet, and crossover baffles. Inspect the baffles to ensure they are present and not severely corroded. If the baffles are concrete and molded into the rest of the tank, venting holes should be present and unobstructed.

• The inlet baffle should be unobstructed and the pipe sealed to the tank.
• The outlet baffle should be unobstructed and the liquid level should be at the bottom of the pipe, not below the pipe or above the bottom of the pipe. The pipe must be well sealed to the tank.

Cleanup and Disinfection

• Wear rubber gloves.
• Discard soiled gloves and sludge toweling in a plastic bag.
• Rinse sticks with bleach water to disinfect before storing

What Can Go Wrong with a Septic Tank and Drainfield?

Like an automobile, septic systems are designed to provide long-term, effective treatment of household waste when operated and maintained properly. However, most systems that fail prematurely are due to improper maintenance.

If you notice any of the following signs or if you suspect your septic system may be having problems, contact a qualified septic professional. Should your septic system fail, contact Lilly’s Septic Service at 425-432-3084 - 360-825-4809 - 253-639-3606.

• Odors, surfacing sewage, wet spots, or lush vegetation growth in the drainfield area
• Plumbing or septic tank backups (often a black liquid with a disagreeable odor)
• Slow draining fixtures
• Gurgling sounds in the plumbing system
• If you have a well and tests show the presence of coliform (bacteria) or nitrates, your drainfield may be failing
• Lush green grass over the drainfield, even during dry weather

Maintaining your Septic System

Maintenance Tips

Homeowners and residents have a great effect on septic system performance. Using more water than the system was designed to handle can cause a failure. Also disposal of chemical or excess organic matter, such as that from a garbage disposal, can destroy a septic system. The following maintenance tips can help your Septic System provide long-term, effective treatment of household waste.

Inspect and Pump Frequently

The most important step to maintaining your septic tank is to remove sludge and scum build-up before it washes into the drainfield.  How often your tank needs pumping depends on the size of the tank, the number of people in your household, the volume of water used, and amount of solids (from humans, garbage disposals, and any other wastes) entering the system. Generally, tanks should be pumped every 3 to 5 years.

Use Water Efficiently

Excessive water is a major cause of system failure. The soil under the septic system must absorb all of the water used in the home. Too much water from laundry, dishwasher, toilets, baths, and showers may not allow enough time for sludge and scum to separate. The less water used, the less water entering the septic system, resulting in less risk of system failure. For water conservation info, see:

Minimize Solid Waste Disposal

What goes down the drain can have a major impact on your septic system. Many materials do not decompose and consequently, build up in your septic tank. If you can dispose of it in some other way, do so, rather than putting it into your system.

Keep Chemicals Out of Your System

Keep household chemicals out of your septic system, such as caustic drain openers, paints, pesticides, photographic chemicals, brake fluid, gasoline, and motor oil. Improper disposal of toxic chemicals down the drain is harmful to the environment, as well as the bacteria needed to break down wastes in the septic system.

Septic System Additives

Adding a stimulator or an enhancer to a septic tank to help it function or “to restore bacterial balance” is not necessary. The naturally occurring bacteria needed for the septic system to work are already present in human feces.

To schedule service call 425-432-3084

Septic System Do’s & Don’ts

Septic System Do’s

1. Inspect your septic tank annually - Septic Tanks should be pumped every three to five years. An inspection by you or Lilly’s Technician may show that you need to pump more or less often. Regular pumping ensures that solids will not flow from the septic tank into the drainfield. Solids  destroy the drainfield, and once a drainfield has failed, pumping will not bring it back to life.

2. Use less water - Reducing the amount of wastewater entering your Septic System may increase its life span, as excessive water is a major cause of system failure. Too much water from laundry, dishwasher, toilets, baths, and showers may not allow enough time for sludge and scum to separate, causing solids to pass out of the tank and into the drainfield, ultimately clogging the pipes. To reduce household water use:

• Limit the use of large water guzzling appliances, such as dishwashers and washing machines.
• Use water-saving bathroom and kitchen fixtures (such as faucets, showerheads, and toilets).
• Spread laundry over the entire week and avoid all loads on one day.
• Fix all faucet and toilet leaks promptly.

3. Direct water from downspouts and roofs away from the drainfield - Additional water from these sources may prevent your drainfield from working properly.

4. Keep cars and trucks off the septic tank and drainfield areas -  This prevents pipes from breaking and soil from becoming compacted. Compacted soils can’t absorb water from the drainfield.

5. Use phosphate-free detergent - Phosphorus is harmful to the environment, as it can deplete oxygen which is vital to fish and other aquatic organisms. The use of phosphate-free detergents, also helps prevent algae problems in nearby lakes and streams.

6. Use non clay based Liquid Laundry/Dishwasher Detergent - Liquid Detergents do not crystalize like powders do and create blockages in the baffles.  Clay based detergents tend to create excess sludge in a Septic Tank.

7. Install risers for easier access. Risers from the tank lids to the soil surface to make maintenance easier and avoid digging charges when you pump your Septic Tank.

For more information about your Septic System and to schedule service contact us at:

Septic System Don’ts

1. Limit garbage disposal use - A garbage disposal adds solids and grease to your system, which could lead to drainfield failure.

2. Don’t use septic tank additives or “miracle” system cleaners - Some of these chemicals can actually harm your on-site sewage system by allowing solids to flow into and clog the drainfield. Some of these additives claim you never have to pump your Tank if you use them.  The reality is that you may not have to pump your Tank regularly but you’ll have to replace you Drainfield instead.  The chemicals can also contaminate ground and surface water. 

3. Don’t dispose of water from hot tubs into the on-site sewage system - Large volumes of water are harmful to the system, and the chlorine can destroy important bacteria in the system. Drain hot tubs onto the ground, away from the drainfield and not into a storm drain.

4. Don’t flush solid wastes into the septic system - These include diapers, cigarette butts, coffee grounds, tampons, condoms and grease.

5. Don’t put strong chemicals, such as cleaning products, down the drain - Household chemicals, such as drain cleaners, paint thinners and floor cleaners, can destroy important bacteria in your septic tank and contaminate ground and surface water.

6. Don’t construct patios, carports or use landscaping plastic over the drainfield - Grass is the best cover for your septic tank and drainfield. Soil compaction and paving prevents oxygen from getting into the soil. This oxygen is needed by bacteria to break down and treat sewage.

 Septic System Do’s and Don’ts by Lilly’s Septic Service

 425.432.3084  253.639.3606  360.825.4809