The best replacement for overflow is carry.

The best alternatives to overflow are rated as following:
★★★★★  carry
★★★★★  underflow
★★  carry out
★★  carry flag
★★  clearfix
★★  skimmer
★  expansion tank
★  overflow
★  skimmer pool
★  drilled
★  diarrhoea
★  carry bit
  no overflow
  backup
  drilled aquarium
  drilled tank
  stackexchange

Your alternative for overflow is not listed? Suggest!
Speaking about overflow, one probably shouldn't forget about scroll.

Other search terms related to overflow and their ratings are:
★★★★★ scroll
★★★ canister filter
★★ two's complement
★ scrollbar
height
buying tub assembly
standpipe
You have in mind a companion for overflow and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of overflow in all years. Click on graph for more.
overflow
carry
underflow