Waste water management

The waste water collection and treatment system consists of three parts:

1. an ‘annular’ collector which surrounds the lake and a treatment plant in the municipality of Marta, managed by Talete spa (formerly by COBALB);
2. municipal sewer networks;
3. private septic tanks of isolated buildings scattered throughout the territory – houses and businesses – not connected to these networks.

The municipal networks collect the sewage water produced within each municipality and carry it to the collector.

The collector consists of 20 main pumping stations connected by sections of pipe about 3 km in length. The pumps push the sewage uphill, and then it flows down by gravity to the next pumping station.

The collector is made up of two ‘arms’: the first starts in the municipality of Grotte di Castro and runs along the north and east coast as far as Marta. The second directs the sewage of Capodimonte until it connects with the first arm near station 20, from which everything is conveyed to the treatment plant. The purified water is discharged into the River Marta.

The plants were built in the 1990s, completed and commissioned from 1996 until 2001.

While the ring collector is designed to safeguard Lake Bolsena, the treatment plant is responsible for protecting the Marta, the river which transports water from the lake.

Throughout the area there are houses and businesses which are not connected either to a municipal network or to the collector. Along the western side in particular there are restaurants, bars, campsites and isolated houses equipped with individual and uncontrolled septic tanks.

What is the state of the sewage system?

Today, at the beginning of summer 2022, the circumlacual system is, after years of grave problems, in a good state. The repair of the treatment plant is also well advanced.

In particular?

The part of the system managed by COBALB has deteriorated since 2007 because the consortium, for political/administrative reasons,  has no longer received regular maintenance funding. In 2013, the pumping stations and the treatment plant were in serious decay. Consequently, the treatment plant has been completely shut since mid-2016. Even in summer 2018, a large part of the sewage ended up in the lake because many pumping stations, especially the SS9, no longer worked correctly.

Finally, after long years of struggle, following the Save the Lake petition of 2011 and thanks to the intervention of the European Union requested by the citizens, the Lazio Region has decided funding to restore the sewage system. On 5 September 2017, the job was awarded to the company which won the tender. In March 2018, work began on the pumping stations. However, quickly the contractor proved inadequate, and, after a period of incertainty, the Region took matters in its own hands concluding a memorandum of understanding with the municipalities, the Province and Talete spa. After that, as you can follow in the “work in progress” news, the situation improved rapidly.

And the municipal networks?

Still in a rather bad state. There are no regular checks on the functioning of the system. As a result, black water penetrates into the soil, and streams are polluted by illegally discharged waste water. In some municipalities waste water mixes with the clean water, (i.e. the rainwater collected in the storm drains). This pollution, apart from contributing to ecological deterioration, creates serious problems for swimming.

The lack of separation of white and black water in municipal areas causes a further problem: in the event of heavy rains, the annular collector will overflow.

In the future?

We hope that all the critical issues of the entire system (listed below) will be solved, one after the other. Further efforts are needed to limit the flow of nutrients into the lake from the sewage system.

The critical issues

Here, in detail, are the critical issues in each part of the sewage system:

1. The annular network managed by COBALB:

• failure of pumping stations and substations,
• spills due to overload caused by rain and/or the increased number of users during the summer,
• leaky pipes.

2. The municipal networks:

• failure of pumping stations and substations,
• spills due to overload,
• leaky pipes,
• no connection of neighbourhoods or houses (with illegal discharges, e.g. in ditches),
• defects in the design of the networks (e.g. lack of separation of white and black water).

3. Houses and businesses not connected to these networks:

• individual houses and businesses throughout the territory with unregulated septic tanks,
• houses and businesses on the west bank not covered by the annular network (with illegal discharges).