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Guide to Septic Tank or Septic System Drain Backup Prevention InspectAPedia®  -     How to prevent a septic backup during heavy use of a private septic tank and system Septic tank cleanout schedule - when do I pump out the septic tank? Complete septic system care & maintenance guide, how often & how to pump out septic tanks Septic System Life Expectancy for septic tanks, septic fields, septic pumps, etc.

This document explains how to avoid septic system backups when heavy use of the system is anticipated. We also refer readers to a septic tank & septic system cleaning schedule - when to pump out the septic tank. If your drains are already backing up, especially during a time of heavy use such as with guests in the home, see SEPTIC BACKUP REPAIR.

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Guide to Avoiding Septic Backups During Heavy System Use

I bought a home in August 2007 that uses a 2000 gallon Septic Tank.  At that time, it was inspected, possibly pumped out and was in fine working order.  We are a family of 4 and for us, we’ve had no problems.  On occasion, we have maybe 8 people visit at a given time.  We are expecting about 60-70 people over for a Birthday Party and my husband is freaking out!  He thinks the septic tank will back up into the drains if we have that many people using the toilets, over a 6 hour period.  My question is: Is my husband correct in thinking that way, will the septic system back up??????  Could you PLEASE answer these questions  AS SOON AS POSSIBLE??????  The party is on 04/26/08.

Why Does the Septic System Back Up During a Party?

Indeed it seems to be just the luck that we are living happily along not giving the septic tank a thought until we have a bunch of guests over for Thanksgiving, Chanukah, Christmas, or a graduation party. Why is it that at events we often see the septic system backing up?

The explanation is that a septic system that backs up during a party was already in trouble, but our usage was modest enough that we just weren't noticing it. The surge of waste water entering the septic tank cannot flow into a flooded drainfield so sewage may back up into the home, usually at the lowest plumbing fixture. Sometimes it's not the wastewater surge but someone flushing something down a toilet that blocks a drain - that's a problem that can be cleared by a plumber using a plumbing snake or drain router. But often the problem is in the septic field itself.

Here are some simple tips for avoiding a septic backup during times of surges in use such as during a party

1. Pump the septic tank before the party: When a septic system is otherwise in good working condition, the septic system stress created by having many people use the sinks, showers, and toilets over a short time is not so much the solid waste as the high wastewater volume in gallons. Very high water usage over a short time can flood a drainfield or septic mound which in turn could cause a septic backup. Pump the septic tank tank right before the event, or the day before. This will give some extra capacity to absorbing this high use resulting in a sudden surge in wastewater volume.
   
   
2. Avoid using water unnecessarily after pump out. That means don't leave running toilets un-repaired, don't leave water running unnecessarily. See Water usage for a table of typical daily residential water usage under normal conditions.
   
   
3. See Don't Flush for a list of things that should not be flushed into a septic system: a list of what's ok and what's not ok to put into septic tanks and building drains.Some of these can cause a system drain blockage and thus a sewage backup into the home.
   
   
4. Regular septic system maintenance, pumping on schedule, is the long term way to protect the system tank and drainfield from early failure and thus to protect from septic system backups. See SEPTIC CLEARANCESand see Ten Steps to Keeping a Septic System Working for a more thorough discussion of how to care for a septic system, or review our complete list of septic maintenance articles at Septic Maintenance Repair
5. See BLOCKED DRAIN REPAIR METHODS for simple methods to clear a blocked drain yourself.

How Much Wastewater Will Be Produced by 60 Visitors During a Party?

In the email example above where our writer assumed there would be up to 70 people visiting the home over a 6 our period, if every visitor uses the bathroom and at each use flushes a toilet twice, that'll be 120 x 4gals = 480 gallons which will be less than the septic tank can hold. So if otherwise conserve water, we have a typical home septic tank of 1000 gallons or larger, and if we start our festival with the tank nearly empty, we're sure to protect the drainfield from flooding during the event.

If the septic system is already in good working order you should be ok.

If your drains are already backing up, especially during a time of heavy use such as with guests in the home, see SEPTIC BACKUP REPAIR.

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SEPTIC SYSTEMS HOME
SEPTIC BACKUP PREVENTION
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SEPTIC SYSTEM DESIGN BASICS
SEPTIC TANK SIZE
SEPTIC TANK TEES
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  TANK PUMPING FREQUENCY TABLE
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  EFFLUENT RETENTION TIME
SEPTIC TANK PUMPING PROCEDURE
SEPTIC TANK INSPECTION PROCEDURE

More Information on Building Diagnostic Inspections and Repairs

• The Septic System Information Website home page for this topic
• Septic Systems Inspection, Testing, & Maintenance- online textbook. Detailed how to inspect, maintain, repair information


• The Home Buyer's Guide to Septic Systems
• SEPTIC TANK PUMPING SCHEDULE When, Why, How to pump the septic tank
• Septic Tank Pumping Procedure step by step photo guideline of how to pump and clean a septic tank - septic tank care
• Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
• Home & Outdoor Living Water Requirements
• Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
• Septic System Design Basics: Choosing Septic Tank Size, Absorption System Size
• Table of Required Septic & Well Clearances: Distances Between Septic System & Wells, Streams, Trees, etc.
• Ten Steps to Keeping a Septic System Working, suggestions from the U.S. EPA, edits and additions by DJF


Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include

• Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
• Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
• Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)

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