Septic Dye Test Procedure
This article contains suggested guidelines for performing a dye test of sewage treatment systems for occupied residential properties. A dye test is a relatively low cost, non-invasive method for the testing of sewage treatment systems, and provides valuable information regarding the present performance of the system.
For the 1st bedroom, assume 200 cap. per day, for each additional bedroom, assume an additional 150 gallons per day.
The above assumes a minimum 1,000 gallon tank which is full or near full. When talking about a septic systems capacity, the assumption is that the tank is full and that the leach lines/field etc. should accommodate the flow of 200 gallons per 1st bedroom and 150 gallons per each additional bedroom.
- Determine capacity of the septic system. I.e. if the building has 3 bedrooms, the septic system should support 500 gallons.
- Determine the amount of dye required to color that amount of water.
- Determine the water flow of the building by using a gallon jug and timing how long it takes to fill that gallon jug. Calculate how long to leave the water on to reach that capacity. I.e. if the water in the building flows at 1 gallon per minute and you need 500 gallons, you would run the water for 500 minutes.
- Flush the required amount of dye tablets down the toilet and run the water in the house to reach “capacity” (see Example below). If the dye does not appear on the ground above the leach field by the time you turn off the water, then the septic system has passed.
A residential home that has 7 bedrooms and the water flows out of the tap at 1.89 gallons per minute would typically have an 1,100 gallon septic system.
To color 1,100 gallons of water to 1PPM, approximately 20 tablets are required.
Determine how long to run the water by dividing the amount of water required by the rate of flow. i.e. 1,100 / 1.89 = 582 minutes
Flush 20 tablets down the toilet and run the water at 1.89 gallons per minute for 582 minutes. If the dye appears above ground around the leach field, then the septic system has failed. If the does not appear, then the septic system has passed the dye portion of the test.