How Much Gravel Do You Need for Your Water Softener Re-bed? March 17, 2022 09:08

How much gravel does a water softener or backwashing filter use? That's a pretty common question we get at Aquatell from customers who are looking to rebuild or re-bed their softener or backwashing filter filter.

Historically, softeners and backwashing filters were built with a gravel under-bedding. It was thought that this under-bedding would help to evenly distribute water through the bed as the system was backwashing, and this would help system performance. There was also some concern that having water softener media or other filtration media sitting against the bare collector basket at the bottom of the tank could increase the likelihood that media could squeeze through and escape the system.

It's been shown more recently that for "residential" sized tanks - those with a diameter ranging up to 12" - that the gravel under-bed does very little to help with water distribution in the tank. For larger tanks there is some benefit, but for residential tanks the benefit is questionable at best.

Advancements in the precision manufacturing and durability of plastic components means that the collector basket at the bottom of the tank is much stronger and more reliable than it was in previous generations.

This points to the fact that using gravel in residential water softener builds likely just adds weight, cost, and some of its own unique troubleshooting issues.  Here at Aquatell we have stopped using gravel in the building of our residential systems altogether.

We still get quite a number of customers who want to use it, because they know it was used when their original softener was built and sold to them. If you'd like to add water softener gravel in your re-bed, the chart below will help you to know how much gravel is required based on the diameter of your tank. This chart works for softeners and backwashing filters of all sorts. The gravel that is typically used is commonly referred to as #2 Grit.

Amount of Gravel Used in Softeners & Backwashing Filters by Tank Diameter

Tank Diameter Pounds of Gravel
8" 10
9" 12
10" 15
12" 20