Maintenance Checklist for Gravity Filtration Equipment
Inspect surface for unevenness, sink
holes, cracks, algae, mud balls or
Dig out sand and gravel at craters of
Locate and repair underdrain system
Chlorinate to kill algae growths.
Probe for hard spots and uneven
gravel layers; if present, treat filter with
Check wash water rise rate and sand
Check sand condition for grain size
growth; sample sand, determine weight
loss on acid digestion, and run sieve
test; acid-treat if necessary, or replace
sand, if necessary.
Check elevation of gravel surface.
Examine gravel for encrustation,
cementation, alum penetration, or mud
balls; if necessary, remove, clean, and
Remove sand from an area 10 feet
square (1 sq m) and inspect an area of
gravel 2 feet square (0.2 sq m) or
larger. If underdrains are deteriorated,
remove all sand and gravel, repair
underdrains, and replace gravel and