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flooding : do’s and don’ts

May 26, 2022


Most septic systems are not damaged by floods because they are buried underground. Tanks and pumping stations may however fill up with debris and silt and will require pumping and cleaning by professionals once the flooding is over. The following recommendations aim to help you prevent damage.


Do not have your septic system pumped at this time! Water may have infiltrated under and around your tanks, unnoticed. When tanks are pumped out, they become much lighter and water may then force tanks upwards. Avoid unnecessary headaches and wait for a more appropriate moment.

Before or during flooding

1. Turn off any power source for your septic installation and store electrical components in a dry area.

2. Do not empty your tanks during flooding, as this may damage your installation.

3. Avoid using your septic system to prevent wastewater backflow inside your residence.

4. Avoid or reduce contact with floodwater.

5. Once flooding is over, see instructions on following page.

After flooding

1. Open all 4 covers to visualize the system’s status.

2. Make sure water has withdrawn at primary reactor and BIONEST® biological reactor outlet inverts.

3. Remove effluent filter and clean using a garden hose, so to remove any particle from filter openings.

4. Cleaning of effluent filter must be done weekly, until particles no longer block openings.

5. Should you have an AUX (BIO-UVTM) alarm and water is at two tanks outlet inverts, please contact Bionest After Sales department.

6. Should you have an HL (BIO-PUMPTM) alarm and water is at two tanks outlet inverts, please contact Bionest After Sales department.

Should clogging of your effluent filter persist after a 3-4 week period, the primary reactor should then be pumped out completely and filled with clear water. The recirculation pump’s electrical supply must be turned off for this operation.


Avoid any contact with wastewater without proper protection equipment. Furthermore, NEVER enter a septic tank. It is a closed space which contains toxic gases, pathogens and low oxygen ; this can prove extremely dangerous, even fatal. Any such work must be performed by trade professionals.

For more information on flooding, visit the following Website : Public Safety and Emergencies Quebec