Energy & Environment

Focus on Wastewater: the Hazard of Ooze

Seepage from outmoded septic tanks is a major threat to groundwater. And it's not just a rural phenomenon.
by | August 2001

Cities and counties have been spending billions of dollars over the past 30 years to do a better job of collecting and treating sewage from homes and businesses in urbanized areas.

But those improvements--and the benefits they bring to the cleanliness of water supplies--are missing something. Millions of Americans are moving out into the countryside where municipal sewers don't reach, and the waste that household systems deposit in backyards poses one of the gravest remaining threats to the country's water quality.

Primitive outhouses are not the problem. They've all but vanished. Local regulations require homeowners without access to central wastewater systems to install septic tanks to dispose of their sewage.

Secluded farmhouses and countryside cabins aren't the only places using their own detached septic systems: so are homes, businesses, and public facilities in once-pastoral resort towns and semi-rural subdivisions close to major population centers. Many of these bedroom communities were laid out just beyond existing sewer systems and never have been hooked up.

All totaled, a quarter of the U.S. population lives in homes that are not connected to wastewater systems, and only half of them are in rural areas. Moreover, with 5-acre homesites cropping up in the midst of sparsely settled farmlands and forests, a third of the nation's new houses are being built with on-site wastewater disposal mechanisms.

Septic tanks are a vast improvement over their predecessors, outhouses and rudimentary cesspools. But they don't provide the fail- safe protection against polluted water that municipally operated sewer systems more often than not deliver. The U.S. Census Bureau calculates that up to 10 percent of the septic tank systems nationwide don't work properly. The U.S. Environmental Protection Agency estimates that 2 million or more malfunction every year, and that translates into 700 million gallons of untreated sewage oozing into the country's watersheds every day.

"Some systems that are failing now should never have been built," says Thomas W. Groves, the New England Interstate Water Pollution Control Commission's wastewater program director. Groves speaks for other state and local officials around the country who express a growing concern about the cumulative impact that polluted septic tank discharges have on rivers, lakes, coastal waters and underground aquifers.


When a septic tank works properly, it's a pretty good technology. Septic tanks hold sewage temporarily while solids partially decay, then they release leftover liquids to be absorbed by an underground drainfield lined with sand or gravel.

When properly sited and maintained, the systems pose no environmental threat. Over the decades, however, many tanks have been installed too close to groundwater or in sandy soils that readily transmit leaking fecal coliform, other pathogens or nitrates. Under the best conditions, septic tank residues need to be pumped out on a regular schedule to keep the system functioning properly. That doesn't always happen.

Then there are capacity issues. In some resort towns, systems installed in summer homes become overloaded when families decide to live there year round. In semi-rural regions on the fringe of booming metropolitan areas, builders equipped new houses with septic tanks they assumed would do the job until sewage agencies ran sewer pipes to newly constructed neighborhoods. That isn't happening in many places, partly because federal sewer construction grants have been replaced with less generous loans. In addition, steel tanks installed decades ago have begun rusting out, and poorly designed drainfields are frequently overwhelmed by overflow from inadequate holding containers.


The issue has captured attention in some states and localities where rules are being written for on-site sewage treatment. Massachusetts now requires septic tank inspections when houses are sold and sets professional standards for firms that install on-site systems. In Pennsylvania, where one-third of the state's residents use septic tanks, local sewage enforcement officers test soils and review plans before granting permits for new installations.

There are roughly 140,000 septic tanks in Rhode Island, and owners are required to get permits for each from the state Department of Environmental Management. DEM regulators have authority to inspect those tanks--and theoretically force owners to repair or replace them- -but officials know that many homeowners can't afford the cost. If Rhode Island really cracked down, "you might have a lot of people out on the streets," says M. James Riordan, Rhode Island's non-point water pollution coordinator. "There are a lot of things government could do that government doesn't do."

It costs $10,000 to $15,000 to replace a malfunctioning septic system, and many homeowners prefer to avoid the costs by simply assuming their systems work fine. Nor do all pay attention to state and local recommendations that they hire somebody to inspect their tanks on a regular basis, much less pay $80 to $100 to have them pumped out every few years--or more frequently for homes where large families are living. "Most people have no idea what a septic system is or how it works," says Susan Licardi, the acting water supply director for North Kingstown, Rhode Island.


Rhode Island's smaller towns offer a microcosm of the septic-tank problem. North Kingstown, for instance, relies on perhaps 10,000 septic tanks to handle sewage in what has become a densely filled suburban area in the southernmost county of the state. Concerned that pollutants are draining into drinking water, town officials in 1999 gave residents three years to have systems inspected and pumped or repaired if necessary. For homes occupying fewer than two acres, the town also can order owners to install nitrogen-treatment systems whenever they expand or improve their houses.

The town of New Shoreham, which is near Block Island Sound, has ordered residents to replace 220 cesspools and renovate failing septic tanks by the end of 2005. Existing tanks also must be retrofitted with filters and other equipment to meet new standards the town has adopted for treating the sewage the tanks handle.

Charlestown, a resort town of 6,500 people on Rhode Island's Narragansett Bay, has had to close salt ponds to shellfishing, partly because fecal coliform and nitrogen are seeping from nearly one-third of the community's 4,500 septic tanks and elementary cesspools where untreated sewage goes straight into holes below the ground. The Charlestown Town Council is moving to require mandatory inspections every three years and fine property owners $500 a day if they don't fix problems within 60 days.

For now, Charlestown residents won't have to replace cesspools "unless the grass is growing green on the lawn and things are backing up into the house," says Roger Pease, the town's wastewater committee chairman. Starting in 2005, however, Charlestown also plans to require that remaining cesspools be eliminated.

Pease figures putting in the simplest modern septic system will cost a resident between $5,000 and $6,000. On more sensitive lands near water, state and town regulations will require more elaborate treatment devices costing up to $15,000. Charlestown has set up a $250,000 wastewater management program that provides low-interest, federally subsidized loans to improve or replace failing septic systems. The town also uses federal grants to help low-income residents cover their initial costs. So far, the town has funded eight loans for upgraded systems that state rules require owners to install when they significantly enlarge their houses.

Charlestown officials figure it would cost millions of dollars to install a central sewage-treatment system. Replacing or repairing an inadequate septic system "is the property owners' responsibility," Pease says. Compared to what they'd have to pay for municipal sewage service, he adds, "property owners are better off with on-site systems."


Homeowners' costs go up, of course, if they live over shallow sandy soils or near wetlands or easily polluted waters. In those areas, state and local policies force them to install more sophisticated on- site technologies that perform much like advanced municipal treatment plants. The most elaborate innovations use greenhouses and artificial wetlands to hold effluent in place while natural processes cleanse it. More commonly, advanced systems inject air to break down septic effluent contaminants or filter it through boxes of sand, peat or another medium such as crushed glass or recycled textiles. Some systems use ozone or ultraviolet light to disinfect the discharges before they're released.

The University of Rhode Island is testing 10 alternative treatment systems in Charlestown. The town now requires schools and commercial developments--as well as apartments built near sensitive waters--to install enhanced systems. North Kingstown requires new commercial developments to install enhanced systems to remove nitrates from effluent unless they demonstrate that conventional septic tanks will be adequate. New or expanded homes in areas where groundwater is close to the surface can be forced to use upgraded effluent-treatment equipment, as well.

In a few communities, neighborhoods have banded together to install cluster septic systems. These collect sewage from a number of homes, apartments or commercial buildings and then run effluent through what amounts to scaled-down municipal treatment plants.

"There's a whole lot of new technologies out there," Pease says. "Some of them are great and others are a little shaky."

Building his new house in Crawford, Texas, President Bush installed a complicated aeration and filtration system that treats sewage and pumps effluent to a drip irrigation system on the ranch. Such elaborate systems use fans, pumps and other mechanical gear that must be maintained more vigilantly than simple gravity septic systems.


Provided they're kept up, the innovations could correct the threats that poorly functioning septic tanks now pose where homes have been built on porous soils or close to sensitive waters. Potentially, they also make it feasible to build more houses on terrain where conventional systems don't provide enough protection.

In Wisconsin, that's sparked an intense debate pitting local governments against state regulators. Builders and developers had been pushing for years for changes to 1980 regulations for new construction. These regulations limited on-site sewage disposal to sites with enough native soil to provide a 3-foot buffer between the septic system and bedrock or groundwater. In effect, the code has functioned as an indirect land-use control that's kept rocky or thinly soiled tracts off limits for development.

Last year, however, the Wisconsin Commerce Department revised the state plumbing code to approve use of sand filters, aerobic treatment and other advanced on-site technologies on parcels with much thinner soil covers. Wisconsin water-quality regulators signed off on the revised code after Commerce agreed to keep 3-foot buffers from groundwater in porous sandy soils. But the League of Wisconsin Municipalities, allied with Wisconsin environmentalists, went to court to challenge regulations they contend will open 9 million acres of poorly drained lands to potentially destructive development.

While it's hard to criticize improved sewage-treatment technologies that work, they doubt the new systems will be reliable enough to allow development to spread safely into some of Wisconsin's most fragile environments.

The issue for many environmentalists is that homeowners aren't answerable to the same sewage-disposal responsibilities as municipalities. To operate wastewater-treatment plants, municipal governments must obtain federal discharge permits and build up financial capacity to replace systems when necessary.

Homeowners who use on-site disposal don't have similar obligations, and local officials remain reluctant to crack down even when the most primitive septic systems start failing. Eventually, "every sewage- treatment system ever built has a 100 percent failure rate," notes Dan Thompson, a former city manager who now directs the Wisconsin municipal league. When that starts happening to on-site systems, "it's very difficult for town supervisors and county supervisors to enforce septic laws on their friends and neighbors."


More from Energy & Environment