Sand and media for water filtration

In the rapid gravity filter (the most common type), the filter layer uses 20 x 40 sand (0.42 to 0.84 mm), with an effective size between 0.45 and 0.55 mm and a uniformity coefficient up to 1.6*. The support layers go underneath, from finer to coarser grain. The filter design rules: check the specification before ordering.

Chemically it is the same mineral, silicon dioxide (SiO₂). In the market, "quartz sand" is usually natural pit or river sand with 95 to 99% SiO₂, and "silica sand" the higher-purity grade, white to greyish, free of organic matter and carbonates, used where the water must not pick up colour or hardness.

Effective size is the sieve opening that passes 10% of the sand (D10): it tells how fine the sand filters. Uniformity coefficient is D60 divided by D10: the closer to 1, the more even the grains, the slower the clogging and the better the backwash. Both come from the grain-size test in the batch report.

In Brazil, ABNT NBR 11799 (filter media: sand, anthracite, expanded clay and gravel), revised in 2024, which covers specification, sampling and tests. Projects with American references call for AWWA B100. We send the batch report with grading, ES, UC and any other tests the project requires.

There is no fixed interval. Replace or top up the bed when head loss rises too fast after backwash, when sand shows up in the filtered water, when the bed level drops, or when mud balls and channels form. In well-run industrial filters, replacement usually falls between 5 and 10 years*.

In 25 kg bags (palletised), 1 t big bags or bulk (by m³), depending on volume and site access. Each batch is labelled with its grain size and comes with the report. We deliver anywhere in Brazil; freight and lead time are in the quote.