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How Much Dye & How Much Water for a Septic Dye Test: Septic Testing Procedure InspectAPedia®  -

• How many gallons of water or how long do we run the water to perform a valid septic loading and dye test?
• How much septic dye powder or how many septic dye tablets should we use to perform a valid septic dye test?
• How to perform a septic loading & dye test, step by step

This chapter provides a table of septic loading and dye test water volumes and septic dye powder or tablets required to perform a valid septic loading and dye test. This table includes details of the Septic Loading and Dye Test procedure for testing the function of septic systems, focused on condition of the effluent disposal section, also known as a leach field, seepage pits, drainfield or drainage field. Also see The Septic Information Website - and see Septic Systems Inspection, Testing, & Maintenance online book on inspecting and maintaining septic systems, of which the document is a chapter. Technical review by industry experts has been performed and is ongoing - reviewers are listed at "References." Comments and suggestions for content are welcome.

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© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

TABLE OF SEPTIC TEST VOLUMES & SEPTIC DYE AMOUNTS - Table of Septic Dye Test Volumes and Septic Dye Requirements

CAUTION: appropriate test volumes may vary depending on the type of equipment installed. Some designs, such as dosing systems, may be approved by local officials but may be capable of only very limited fluid handling capacity per hour. Information provided by seller, realtor, visual inspection, or neighborhood history may indicate if special limited-capacity systems are installed. The following guidelines pertain to conventional tank and absorptions systems such as tank and trench-line drainfields.

The following table is a general guide to selecting the volume of test water and the amount of septic tracer dye needed to perform a septic loading and dye test. If you're asking "how much septic dye" or "how many septic dye tablets" should I use, look here and also look at the instructions from the manufacturer of your septic dye.

Notes to the Table of Septic Dye Test Volumes and Dye Amount

• Before selecting a test volume the inspector needs to know something about the design of the onsite wastewater disposal system that is installed. The table above assumes a conventional septic tank and drainfield are installed. If a dosing system, pumping system, or other special designs are present, flooding the system beyond the design-specifications for a given time period could damage the system or produce inappropriate test conclusions.
  
  
• The validity of a septic loading and dye test is not based on the length of time that water is run into building fixtures - though readers will see many inspectors who use this criterion. Rather the validity of the test depends on the total volume of water that was placed into the system along with other obvious procedural steps such as making sure that the fixtures used to introduce water into the system indeed drain into the septic system being tested and not to somewhere else.
  
  
• Calculating Septic Tank Volume: see Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow calculating septic tank volume and septic tank size required
  
  
• Tramfloc Inc., (Tempe AZ) a producer of dye tablets and liquids, indicates the following dye amounts and capabilities:
• One Bright Dyes Tramfloc Dye Tablet will color 60 gallons of water. So to color 600 gallons you'd need to use 10 tablets.
• One pound of Tramfloc "Bright Dyes Standard Blue and FLT Yellow/Green will treat 120,000 gallons of water.
• One pound of FWT Red Dye (more expensive to use) will treat 60,400 gallons.
• One pint of liquid Standard Blue and FLT Yellow/Green will treat 12,500 gallons
• One pint of liquid Red 25 will treat 6,250 gallons
• "Treat" in this instance means that a strong, easily visible color is produced.
• Where existing surface water is murky brown colored, Tramfloc recommends the FLT Yellow/Green tracer dye.
• Tramfloc Inc. informs us that their septic dye products are non-toxic and are rated for use in potable water. However inspectors who put any dye product into a toilet which overflows or into a drain which is leaking will stain the building.

DETERMINING TEST VOLUMES - Recommended Septic Loading: How to Determine Dye Test Water Volume, and Amount of Septic Dye

FIXTURE FLOW RATE - Estimate the test fixture flow rate during a septic test

Based on field experience, actual test measurements at 25 residences served by private well systems and observations of typical flow and pressure at residences served by municipal water supply systems, we find that 3 gpm is a reasonable estimate of flow from a single tub or un-screened sink fixture. Most private systems can deliver this volume.

Actual quantitative flow rate measurements taken at a single fixture at a single time are dangerously misleading since variations in pump pressure, pipe obstructions, valve settings, can affect flow.

If accurate quantitative measurement of flow rate is needed, and remembering that you're measuring the flow provided by the pump, pipes, valves, and fixtures, not the well flow capacity, a simple procedure is the use of a 5-gallon bucket under the test fixture, and a stopwatch. However multiple measurements may be needed to evaluate the variation in flow rate during the pump on-off cycle.

HOW TO SET THE SEPTIC TEST WATER VOLUME - determine the septic loading test water volume

Some authorities commonly test by loading the system with 50 gallons/bedroom over an hour - the likely maximum load for a typical residential system. A typical trench-type absorption field would contain this volume of water even if there were no percolation during the test period. Therefore breakout or failure at these volumes is a reasonable sign of system failure or inadequacy.

Typical septic system design handles 150 gallons/bedroom/day. [Ref. 30, Oberg, citing "Private Water Systems Handbook," produced by the US Dept. of Agriculture Cooperative Extension.]

Lockwood in our own article Septic Systems - An Engineer's View uses this same figure of 150 gallons/bedroom/day to estimate water usage in a typical residential building. Also see Home & Outdoor Living Water Requirements for more detail.

Keith Oberg (ASHI, Binghamton NY) computes that a standard leach line for soils in central NY range from 90 lineal feet with a 3 foot wide trench and a percolation rate of 1" in 5 minutes, to 375 lineal feet of 3 foot trench with a perc rate of 60 minutes.

The gravel in a standard trench leaves approximately 38% of total volume available to contain effluent. Therefore, assuming no percolation during the test period, the water level will rise 2.35" in a 90' trench and .56" in a 375' trench. (Double these depths for more narrow gravel trenches.) These are not excessive increases in a leaching field which is typically set at least 12" below the surface with 18" depth of gravel as standard practice. It is therefore apparent that an adequate septic system should not break out when subject to this test.

Oberg applies this same test to all septic systems of all types, including sand mounds, sand filters, aeration ponds, jet aerators, drywells, cesspools, etc. If there are multiple systems the water load is split on each system and a 33% extra water load is added to account for errors in estimation of the percentage of total use.

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SEPTIC SYSTEMS HOME
SEPTIC SYSTEMS ONLINE BOOK
SEPTIC DYE TEST PROCEDURE
HOW TO PERFORM A SEPTIC DYE TEST
WHAT TO DO FIRST
OUTSIDE SEPTIC INSPECTION
  IMMEDIATE FAILURE EVIDENCE
  LOOK FOR COMPONENTS
  DIFFICULT SEPTIC SITES
  RECENT SEPTIC WORK
  SEPTIC SAFETY
STEP BY STEP SEPTIC TEST
  INSIDE SEPTIC TEST STEPS
  WATCH FOR INSIDE
  OUTSIDE SEPTIC TEST STEPS
  SEPTIC FAILURE SPOTS
  SPOTTING SEPTIC BREAKOUTS
SEPTIC TEST VOLUMES & DYE AMOUNTS
  SEPTIC TEST WATER & DYE TABLE
  SEPTIC TEST FIXTURE FLOW RATE
  HOW TO SET THE SEPTIC TEST VOLUME
REPORTING SEPTIC TEST RESULTS
PUMP THE SEPTIC TANK
SEPTIC DYE TEST WARNINGS

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

More Information on Building Diagnostic Inspections and Repairs

• Return to the septic system textbook: Inspecting, Testing, & Maintaining Residential Septic Systems
• The Septic Information Website
  
  
• Safety Warnings to Septic System Inspectors
• Testing Water for Real Estate Transactions - Water Test Cheating Warnings for Home Buyers and Home Inspectors.
• Home & Outdoor Living Water Requirements
• Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow calculating septic tank volume and septic tank size required
• How Big Should the Leach Field Be? - table of soil percolation rate vs. field size
• The Home Buyer's Guide to Septic Systems
• Material Safety Data Sheet MSDS for Red Septic Dye from Tramfloc.
• MSDS for Septic Dye Tablets from Tramfloc.
• MSDS for Septic Dye Liquid from Tramfloc.
• Septic Dye Technical Data Bulletin from Tramfloc.
• Tramfloc, Inc. source of septic system testing tracer dyes
• Bright Dyes Inc. source of septic system testing tracer dyes
• Pollard Water source of septic system testing tracer dyes

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