Sewerage

How sewerage works

If the aqueduct is used to deliver large quantities of drinking water to population centres, the sewerage system is used to remove harmful water quickly and continuously. It includes the connections to individual users (domestic or industrial) and the sewerage collectors, which converge into the "backbone" of the system to be taken to the water treatment plant. In fact, human activity discharges large quantities of pollutants into water. That is why dirty water must be collected and cleaned up by means of a treatment process before it is released into rivers and seas.

Harmful waters are understood to mean both waste water and rainwater (stormwater). Waste water includes domestic water, which comes from homes but also from public and private buildings, water generated by street cleaning and watering, and water used by industrial plants. The sewerage system generally flows naturally: waste water flows by gravity from a built up area to the treatment plant. Along this route, depending on the obstacles found in the territory and the height requirements, there may also be lifting plants that use a series of electric pumps to lift the waste water mechanically to the next stage of the route.

133

Municipalities served by our sewerage service

The sewage network

The sewage system is the complex of works that carry the waste water from our homes, in some cases industrial waste water and part of the rainwater to the water treatment plants. Waste water is carried to the treatment plants to be treated and then cleaned before “returning” to nature.

6.528 Km

of sewage networks

Waste water analysis

Treated water must be analysed and tested before being returned to the environment. This is what we do in the three company laboratories that examine the incoming and outgoing waters at the treatment plants operated by Gruppo CAP. In particular, the laboratory at the Pero plant also controls the quality of the waste water discharged from production facilities into the sewerage system. Checks are carried out in accordance with the requirements of current legislation and according to a sampling schedule submitted each year for approval to ARPA, the Regional Agency for Environmental Protection of the Lombardy Region.

More than 4000 checks are carried out each year on the treatment plants and more than 700 checks are carried out on industrial discharges. The main parameters analysed are:

Chemicals (COD, BOD5, Total solids, Total nitrogen, Total Phosphorus, etc.)
Aromatic and chlorinated solvents
Surfactants
Metals (cadmium, chromium, iron, nickel, lead, copper, zinc, etc.);
Microbiological (E.Coli, Salmonella, etc.)

In addition to the internal checks carried out in the company laboratories, ARPA carries out external checks in accordance with the general criteria set out by the Lombardy Region regarding plant inspections, the collection points of the samples to be analysed and the frequency of sampling.

The Pero and Peschiera Borromeo laboratories are accredited according to UNI CEI EN ISO 17025:2018 in compliance with the provisions set out by ACCREDIA Regulation RT-08 (accreditation no 697) for the tests listed below.

Elenco prove accreditate dal laboratorio

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Water treatment

Find out the CAP Group water treatment system

Networks and citizens

We pay special attention to our customers and receive many rewards in return. Here are the results of research on a sample of 2600 customers in the territory who were asked about our services.

97,9%

Satisfied with the water service

96,7%

Satisfied with the sewage network

Acqueduct

Safe water

Water analysis

The network and wells

Water treatment