Sand filters and
biofilters can
effectively treat
wastewater —
even in areas
with poor soils
JANUARY JLC 1997
Around a quarter of America's homes have
an on-site sewage disposal system, usually
consisting of a septic tank and leach
field. On-site septic systems are popular
because they cost much less than connecting
to a sewer line, especially in
spread-out suburban or rural areas.
But on many sites, the classic septic
tank and leach field system won't work
because the soils aren't suitable for adequately
treating septic effluent. In soils
that drain too slowly, septic systems can
fail by causing effluent to pond on the
surface or even to back up into the house
(an "operational failure"). In soils that
drain too fast, or