Suffolk County Executive Steve Bellone signed a bill Thursday that bans the installation of new cesspools as the primary way of treating waste.

Septic tanks will have to be used if they are not already installed.

Environmentalists say cesspools cause nitrogen pollution, which damage the water quality on Long Island.

“Not using cesspools means we'll have less nitrogen and less pollutants going into our groundwater and into our marine water environment -- lakes, streams and rivers,” says Adrienne Esposito, of Citizens Campaign for the Environment.

The new law only applies to those who have to replace a failing cesspool.  There could be other policies put in place regarding septic systems over the next few years. Those could include requiring an advanced nitrogen reducing system in any new construction when an old system needs to be replaced or when a property is sold.

Bellone says the new law is a small step in the right direction.

“It lays the foundation to move us toward replacing systems with advanced septic systems that will treat for nitrogen and help us to reverse the decades of decline in water quality,” says Bellone.

Starting next July, sewage treatment companies will have to notify the county when they do any kind of pumping or replacement of existing septic systems.