Backwashing is a maintenance process where water flows in the reverse direction through a filter to remove accumulated particles, contaminants, or precipitates that have been trapped during normal filtration. All filters need to be backwashed or replaced at some point. If you are unsure if your filter(s) need backwashed or replaced, check the manufacturer's instructions.
Examples of devices that require:
Backwashing: Granular media filters, oxidizing filters, whole house activated carbon filters, water softeners, and neutralizing filters
Replacement: Sediment cartridges, carbon block filters, granular activated carbon cartridges, reverse osmosis pre-filters and membranes, inline filters (refrigerator, under sink), and ceramic filters
This video is being shown for educational purposes only. The Private Well Class does not endorse any products, suppliers, or independent treatment professionals.
The above video is a 3D animation of how backwashing a filter occurs. It shows how unfiltered water enters the treatment device from the left. It flows through the filtration system where contaminants (the blue dots) get trapped on the filter or media that is being used. The water then exits to the right, free of contaminants. When the filter accumulates enough debris and particles, it is time for the device to go through a backwash cycle. The water reverses the direction of the flow as shown by the multiple red arrows. The accumlated debris and particles are flush out of the device through the drain outlet.
How do I know when to backwash my treatment device?
Devices will have either an automatic (timer, flow meter) or manual (pressure drop, visual inspection) signal that it is time to backwash. The frequency depends on water quality, system size, and media type. Some systems may need daily backwashing, while others only need it done weekly or monthly. If an automatic signal is present, set it for the middle of the night to prevent water usage during the backwashing cycle.
Maintenance is essential for devices that utilitze backwashing. Be sure to regularly check:
The backwash schedule
Drain line for clogs or leaks
Media condition (some types degrade over time)
System settings (especially after power outages)
How much water does backwashing take, and what were does it need discharged to?
Backwashing can often use 30 to 100 gallons of water per cycle, so implement water conservation measures when using a private well. Always direct the discharge to an appropriate location such as:
Sanitary sewer (if allowed)
Dry well
Designated drainage field
Note: If the home is on a septic system, it is important to ensure that it can handle this volume.
A water treatment device should never be discharged into storm drains, surface water, or areas where it could cause erosion or contaminate drinking water sources.
Follow Local Regulations: Always check with your local health department or environmental agency. Some areas have specific rules about where and how backwash water can be discharged, especially if it contains iron, manganese, or other minerals that could affect soil or water quality.
Additional Resources:
Filter Backwashing. National Environmental Services Center. 2005.
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