This document discusses how a septic tank system works, including that solid waste settles to the bottom of the tank while liquid filters through the soil and is broken down by microorganisms, and that the tank needs periodic cleaning every 3 years to remove scum and sludge as solid waste builds up over time.

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3. Latrine
Watertight
settling tank
Soakaway

4. Soil filters
water, like a
sieve
Microorganisms
eat the dirt

5. Can make the septic
tank smell. Need
more often emptying Some chemicals will
kill off the bacteria
and stop the septic
tank working
Non biodegradable
waste will block the
tank

6. The tank needs periodic
cleaning to remove scum and
built up sludge about every 3
years.
Waste water needs to
remain in tank for
minimum 24 hrs to ensure
it settles
Its called a Septic tank as the waste
is degraded under anaerobic
conditions (no oxygen)