Monitoring water and water networks: how does it work?

Water flows through complex underground networks that are often invisible but vital. From the source to the tap, and all the way to the wastewater treatment plant, every metre of pipe, every reservoir and every connection plays a part in our everyday lives.

To ensure that this system works flawlessly, it is essential to monitor the entire network, detect leaks, control quality and anticipate malfunctions. Through the use of smart technological solutions, the management of water networks has become more precise, more responsive and more connected.

But how does this work in practice? What tools are deployed? Who is responsible for this monitoring? This article gives you the keys to understanding what is at stake and the mechanisms involved in monitoring water and water networks.

What is a water and water network monitoring system?

There's a lot more to monitoring a water network than just reading a meter or inspecting a pipe. It involves organising a continuous watch, at various levels, to ensure that water flows safely, without loss or contamination, and with a constant service for users.

A monitoring system combines physical tools (sensors and connected valves), digital platforms (supervision software and cloud interfaces) and an analytical and response approach.

These systems are designed to:

Detect water leaks and other anomalies in the network (excessively high pressure, pollution, etc.),

Optimise operations in the field,

Safeguard the drinking water supply,

Monitor network performance (output, pressure, levels, flows),

Anticipate incidents and peaks in consumption.

They concern drinking water networks, sewerage networks and sometimes rainwater. Their effectiveness is based on the interconnection between the various components in the network and on the ability to transform data into actual decisions.

They enable managers to evolve from a reactive approach to one based on anticipation, to the benefit of organisations, local authorities and citizens alike. This means they can monitor the performance of drinking water and wastewater infrastructures in real time or on a periodic basis.

These systems are based on instrumenting the network, and collecting, transmitting and analysing data.

A drinking water supply network comprises a number of essential components:

Pumping and treatment stations: these capture the raw water, treat it to make it drinkable and then direct it to the distribution areas.

Storage reservoirs: these provide a sufficient supply of water to cover daily demand and peak consumption (e.g. water towers).

Transport and distribution pipes: these carry the water from the plants or reservoirs to the various service points, while maintaining constant pressure.

Hydraulic devices (pumps, fittings, filters, etc.) to enable water to be conveyed.

Individual connections, or household-to-mains water connections: these link each home, building or establishment to the public network, thereby enabling targeted distribution.

Monitoring points (meters, sensors and valves): these collect data in real time on the volumes, quality and pressure of the water so that the network can be managed with great precision.

In terms of wastewater treatment, there are:

Wastewater collectors: these collect wastewater from homes and businesses and transport it to treatment facilities.

Rainwater and run-off collectors (as climate change is bringing about low water levels and flooding, it is important to manage rainwater effluent).

Pumping stations: these lift wastewater in areas with a shallow gradient so that it can continue on its way to the treatment plant.

Wastewater treatment plants: these treat wastewater to eliminate unsuitable elements before it is discharged into the natural environment.

Outlets for final discharge into the natural environment: these are the points where treated water is returned to rivers or lakes, in compliance with environmental standards.

Monitoring takes place at every level to track the flow of water, identify losses, analyse quality and detect faults.

What are the main water distribution architectures?

There are three main types of organisation for distribution networks:

Branched network: straightforward architecture in which the water follows a main route with secondary branch lines. Although it is easy to implement, it is vulnerable to interruptions if there is an incident on the main supply line.

Mesh network: a network of interconnected loops, making it more resilient to service interruptions. It enables flows to be redirected if a section of the network is affected, thereby providing better continuity of service.

Combined network: a combination of the two above, suitable for complex areas often found in conurbations. It offers a good compromise between redundancy, flexibility and ease of maintenance.

Each configuration requires a suitable monitoring strategy to guarantee continuity of service and react quickly in the event of an incident.

Who manages water networks?

In France, the management of water networks has been decentralised to local authorities. The municipalities or inter-municipal bodies own the drinking water and wastewater infrastructures. They must oversee the continuity of the public service, the quality of the water supplied and the preservation of the resource.

Two management models exist side by side:

Direct management: the local authority operates the water service directly, using its own staff, equipment and budget.

Delegated management: the local authority entrusts the running of the service to a private company under a public service delegation contract. This company is responsible for maintaining the water networks, as well as monitoring and billing, under the supervision of the local authority.

In both cases, strategic decisions remain in the hands of local elected representatives, but the effectiveness of the service also depends on the technical and human resources deployed.

Controlling the quality of the water that is distributed is a regulatory obligation governed by the Public health code. This control is carried out by the regional health agencies (ARS), under the authority of the Ministry of Health.

The regional health agencies take regular samples at the water production and distribution points. These analyses are used to check that the water complies with over 60 quality parameters.

Controls can be stepped up in the event of alerts, accidental pollution or in sensitive areas. At the same time, network operators (whether public or private) carry out their own continuous internal monitoring, to provide an immediate response.

This dual monitoring - external by regional health agencies and internal by operators - is an essential guarantee of consumer health safety.

What are the 3 criteria for drinking water quality?

Drinking water must satisfy three major criteria, each guaranteeing a specific aspect of consumer safety and comfort:

1. Microbiological criteria: this involves checking that the water is free from pathogenic micro-organisms such as coliforms, enterococci, E.coli and Legionella. For example, the presence of E.coli in a sample is a direct indicator of contamination, and may render the water unfit for immediate consumption.

2. Physico-chemical criteria: this criterion covers a range of measurable parameters such as nitrate levels, pesticide residues, heavy metals (lead and arsenic), pH and conductivity. Water with nitrate levels above 50 mg/l, for example, is considered non-compliant according to European standards. An excessively acidic or basic pH can also cause corrosion in pipes and impair water quality.

3. Organoleptic criteria: these parameters concern the taste, odour, colour and general appearance of the water. Even if water is microbiologically and chemically compliant, an unpleasant odour or metallic taste can make users suspicious and discourage them from drinking it. For example, a brownish discolouration linked to the presence of iron or manganese may give cause for concern, even if there is no immediate health risk.

These three criteria are continuously monitored by the operators and regularly checked by the regional health agencies to guarantee the quality of tap water throughout France.

Why monitor water and water networks?

Continuous monitoring of water networks is now essential to guarantee a reliable, economical and sustainable service. It addresses a number of challenges:

Maintain the healthy quality of the water, by immediately detecting any deviation in parameters (turbidity, chlorine, pH, etc.),

Optimise network efficiency by quickly locating leaks or discreet losses,

Protect the environment, by preventing overflows, pollution or accidental discharges into the natural environment,

Tighten security, by identifying anomalies, intrusions or technical risks that could affect users,

Anticipate requirements and emergencies using real-time data, so that action can be taken before incidents escalate.

In brief

Monitoring water and water networks has become a necessity. It means that risks can be anticipated, the quality of the public water service can be guaranteed, and a vital resource can be preserved in the face of climatic hazards and increasing demands. The benefits of these systems are legion, whether as part of the energy transition for local areas, regulatory self-monitoring for wastewater treatment, or even ongoing diagnostics for drinking water.

With connected technologies, automation and data analysis, today's infrastructure managers can take proactive action, optimise their response and bolster the resilience of their infrastructures. The combination of performance, through technical expertise, and monitoring, through supervision tools, paves the way for sustainable, efficient and accountable water management, for the benefit of each and every one of us.