I hope this information helps.” see less I wrote to Downy at the contact email and just received this reply: “All of our laundry detergents have been thoroughly evaluated and are safe to use in homes with a properly functioning septic system.

Is Ultra Downy septic safe?

Yes. P&G evaluates environmental safety of all ingredients used in our products. All Downy products are expected to be safe as long as they are used as intended and the septic system is functioning properly.

Can I use biological washing powders with septic tank?

Products such as bleach, chemical cleaners and biological washing powders should be avoided or used sparingly as these reduce biological activity and can therefore affect the efficiency of the system. The advised distances from buildings and watercourses are the same as for a cesspool, as is the legislation.