Just as the title asks, is it safe to use products like Liquid Plumr or Drano in a Septic system?
As a one-off use, Drano® is fine provided you aren't cleaning your floor or doing a couple loads of whites on the same day.
What independent studies say:
According to a 2004 paper by Cornell researchers titled "Household Chemicals and your septic system", despite the assertions of the corporations making Drano® and Liquid-Plumr®, these products can indeed destroy the beneficial bacteria in your tank. If used in excess, or in combination with other cleaner such as bleach you may encounter problems.
Further, the 1987 study preformed by Mark Gross for the Arkansas water resource title "Assessment of the Effects of Household Chemicals Upon Individual Septic Tank Performances" claims that for a 1,000-gallon septic tank, the maximum allowable maximum daily dosage of common cleaners is as follows:
- Liquid hypochlorite bleach: 1.3 gallons
- Pine cleaner: 2.5 gallons
- Crystal drain cleaner: 0.65 ounces
Many plumbers claim that one should worry about the impact of what ever it is that caused your drain in the first place (fats, sanitary napkins, large solids, washing machine lint), than the use of the drain cleaner it self. For this reason, it is preferable to snake your drain rather than clear it with a Drano®.
According to Drano
Will Drano® products harm my septic system?
No, all Drano® products are septic safe drain cleaners and will not upset the bacterial action in septic systems. Follow the package instructions for the right amount of product to use. Use Drano® Max Build-Up Remover on a monthly basis to replenish the bacteria in the septic system that help break down toilet paper and organic matter in pipes.
And Liquid Plumr
Is it safe to use Liquid-Plumr® products if I have a septic system?
Yes. It’s safe to use Liquid-Plumr® products if you have a septic system. The ingredients degrade rapidly and will not harm the bacteria in your tank.
In what way are you using "safe"? It is not supposed to damage the pipes where some stronger drain cleaners will etch metal pipes. As far as chemicals in the tank it may affect the bacteria until diluted but this is true with even soap and laundry detergent. Over all I would expect infrequent use and that should not damage the system so in that regard I would say it is safe.