The best replacement for backwash is washback.

The best alternatives to backwash are rated as following:
★★★★★  washback
★★  waste
  swash

Your alternative for backwash is not listed? Suggest!
Speaking about backwash, one probably shouldn't forget about sand filter.

Other search terms related to backwash and their ratings are:
★★★★★ sand filter
★ air scour
You have in mind a companion for backwash and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of backwash in all years. Click on graph for more.
backwash
washback
waste