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SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SEPTIC CARE INSTRUCTIONS
SEPTIC D-BOX INSPECTION
SEPTIC DRAINFIELD FAILURE DIAGNOSIS
SEPTIC DYE TEST PROCEDURE
SEPTIC FAILURE SIGNS
SEPTIC INSPECTION & TEST GUIDE
SEPTIC LIFE EXPECTANCY
SEPTIC SUPPLIES & PARTS
SEPTIC SYSTEM DESIGN ALTERNATIVES
SEPTIC SYSTEM DESIGN BASICS
SEPTIC SYSTEMS, HOME BUYERS GUIDE to
SEPTIC SYSTEM SAFETY WARNINGS
SEPTIC TREATMENTS & CHEMICALS
SEWAGE BACKUP PREVENTION
SEWAGE EJECTOR / GRINDER PUMPS
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SINKHOLES, WARNING SIGNS
SOAKAWAY BED FAILURE DIAGNOSIS
SULPHUR & SEWER GAS SMELL SOURCES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
TREATMENTS & CHEMICALS, SEPTIC
VIDEO GUIDES: Septic Videos
WATER CONSERVATION MEASURES
WATER SOFTENERS & CONDITIONERS
WATER SUPPLY & DRAIN PIPING
WATER, WELLS, WATER TANKS: TESTING GUIDE
WASHING MACHINES & SEPTIC SYSTEMS
WASTEWATER TREATMENT BASICS
WINTERIZE A BUILDING
This article 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.
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TABLE OF SEPTIC TEST VOLUMES & SEPTIC DYE AMOUNTS - Table of Septic Dye Test Volumes and Septic Dye Requirements
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.
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
DETERMINING TEST VOLUMES - Recommended Septic Loading: How to Determine Dye Test Water Volume, and Amount of Septic Dye
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.
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.
The first links below allow you to purchase septic dye directly from the producer. Also see Septic Dye MSDS.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Design Manuals for Septic Systems