Septic Systems and Stormwater

Why this matters

Customer-side stormwater management directly affects septic system performance. Stormwater overwhelming the system + drainfield is a common cause of failure that customers don't connect. A septic contractor educating customers on proper stormwater management prevents many system issues + protects the customer's investment.

How stormwater affects septic

The customer's stormwater (rain + roof drainage):

• Should drain AWAY from septic
• Should NOT enter the septic system
• Should NOT saturate the drainfield

When stormwater enters the septic:

• Overloads the tank
• Pushes solids to the drainfield
• Drainfield saturated
• System failure accelerated

When stormwater saturates the drainfield:

• Field can't absorb septic effluent
• Backup into the home
• Damage to the field

Customer's stormwater management is critical.

Common customer errors

Each is a documented cause of failure.

Best practices

For the customer:

1. Roof downspouts: discharge at least 6-10 ft from drainfield
2. Sump pump: discharge well away from septic
3. Foundation drains: connected to storm drain, NOT septic
4. Yard drainage: away from drainfield
5. Paved surfaces: slope away from drainfield

Each is preventable through awareness.

Foundation drains specifically

For customer's home:

• Foundation drains collect groundwater
• Many are connected (mistakenly) to septic
• Verify customer's situation

If connected to septic:

• DISCONNECT immediately
• Connect to storm drain OR daylight discharge
• Customer's system load reduces

Sump pump considerations

For customer's basement sump:

• Sump pump discharges water
• Often near foundation
• Should discharge AWAY from septic
• 10+ ft minimum

When the customer's drainfield is in a low spot

Original installation:

• Sometimes drainfields were installed in low spots
• Customer's stormwater concentrates there
• System failure faster

Solutions:

• Improve drainage away
• Customer's grading work
• Sometimes new drainfield in better location

Drainage system options

For customer's property:

Each addresses customer's stormwater.

Yard grading

Customer's home should:

• Slope away from foundation (typically 5% within 10 ft)
• Slope away from septic
• Not pond at the drainfield
• Customer's grading important

Grading is the foundation of stormwater management.

When the customer reports basement water

Multiple causes:

Each requires investigation.

When the customer's septic is failing from stormwater

Specific failure mode:

1. Drainfield can't absorb during storms
2. Sewage backs up
3. Customer's home affected

Solutions:

• Drainage improvements (away from drainfield)
• Customer's stormwater management
• Sometimes drainfield replacement (with better location)

Customer education

For the customer:

1. "Stormwater is the biggest threat to your drainfield"
2. "Keep roof + foundation water away from septic"
3. "Verify all drainage flows away"
4. "Annual inspection during heavy rain helpful"

A trained customer protects the system.

When the customer's home is on a slope

For sloped properties:

• Stormwater concentrates downhill
• Septic placement considered
• Customer's grading + drainage important
• Specific design

Customer's site conditions matter.

Coordination with the customer's other contractors

For comprehensive drainage:

• Landscape contractor
• Plumber
• Excavator
• Septic contractor

Customer's project benefits from coordination.

Common installation considerations

For new installations:

1. Site survey identifies water flow
2. Septic placed appropriately
3. Drainage planned at install
4. Customer's long-term management

Original installation considers stormwater.

When the customer adds a building

For additions / outbuildings:

• More roof area = more stormwater
• More foundation = more drainage
• Verify septic accommodation
• Customer's project septic-aware

Customer's addition planning matters.

When the customer paves

For driveway / patio additions:

• More runoff
• Less absorption
• Customer's stormwater concentrates
• Septic considerations

Customer's project should be septic-aware.

When the customer landscapes

For landscape projects:

• Drainage patterns may change
• Septic considerations
• Customer's project planning

Cross-trade with landscape designer.

Local code requirements

For some jurisdictions:

• Stormwater management plan required
• Septic + stormwater coordinated
• Customer's compliance

Verify customer's local requirements.

Customer's storm response

When heavy rain:

• Verify septic working
• Reduce water use during heavy rain (if customer's drainfield is challenged)
• Customer's awareness

A customer's preparation.

When the customer has chronic issues

For ongoing problems:

1. Investigate stormwater
2. Identify customer's specific drainage issues
3. Comprehensive solution
4. Customer's commitment to improvement

Many "septic failures" trace to stormwater.

Specialty: French drain integration

For drainage:

• French drain collects subsurface water
• Connected to safe discharge
• Coordinated design

Specialty installation.

Customer's neighbor considerations

For shared drainage:

• Neighbor's stormwater may flow toward customer's septic
• Coordination required
• Customer's protection

When the customer's neighbor adds buildings

For shared property line:

• New runoff toward customer's septic
• Customer's coordination with neighbor
• Customer's protection

Sometimes complex.

Customer's grading verification

For customer's home:

1. Walk the property
2. Identify water flow paths
3. Recommendations

A site walk reveals stormwater patterns.

Specialty: bioretention

For some customers:

• Bioretention area away from septic
• Customer's stormwater absorbed
• Septic protected
• Customer's landscape choice

Increasingly popular.

When the customer's pumping increases

For increased pumping needs:

References

• EPA stormwater regulations
• Local stormwater codes
• USGS groundwater protection
• Manufacturer documentation
• Manuall internal: Septic System Types, Drainfield Diagnostic, Septic Maintenance Customer Guide