Supporting the Delivery of Specialist Water and Sewage Projects

Water infrastructure refers to the systems that collect, treat, store and distribute clean water, as well as the networks that transport and manage wastewater and sewage. This includes pipelines, pumping stations, treatment plants, reservoirs and sewer networks that ensure water supply and effective drainage.

Regular water treatment is the process of taking raw water from sources like rivers, reservoirs or groundwater and removing impurities so it becomes safe drinking water. This typically includes screening, filtration, chemical treatment and disinfection. It ensures water meets strict standards before it reaches homes and businesses.

Wastewater treatment, on the other hand, involves cleaning used or contaminated water from households, industry and businesses. Treatment removes solids, organic matter, chemicals and pathogens so the water can be safely returned to the environment. It usually includes screening, settling, biological treatment and disinfection.

Together, these processes ensure both incoming clean water and outgoing wastewater are managed safely and in line with statutory drainage and wastewater obligations.

A sewage treatment plant typically works in stages:

• Collection & screening to remove large debris.
• Primary treatment where solids settle out.
• Secondary (biological) treatment using bacteria to break down organic matter.
• Final clarification to separate treated water from biological solids.
• Disinfection before discharge.

These processes ensure wastewater is treated in line with statutory obligations for drainage and sewage management.

A Water Treatment Plant (WTP) processes raw water (from rivers, reservoirs or groundwater) to produce safe drinking water.

A Wastewater Treatment Plant (WWTP) treats used or polluted water so contaminants are removed before the water is released back into the environment.

They work in opposite directions: WTPs make water safe for consumption, while WWTPs make water safe for discharge.

Hydrogen sulphide forms when organic matter decomposes in low‑oxygen sewer environments. Even at low levels, H₂S can cause headaches and nausea; at higher concentrations it can lead to respiratory failure. It is also heavier than air, meaning it accumulates in tanks, pipes and confined spaces, making effective ventilation and gas monitoring essential. While not directly stated in sources, this hazard is inherent to wastewater networks described in statutory drainage and wastewater management guidance.

Read our best practice article on the importance of H₂S in the water sector >

AMP8 is the eighth Asset Management Period, covering 2025 - 2030, and sets the investment, performance and environmental targets for water companies in England and Wales. It is overseen by Ofwat, the industry regulator.

AMP8 is driving major infrastructure upgrades because the sector faces increasing pressure from:

• Climate change and extreme weather
• Ageing pipes and treatment facilities
• Stricter environmental expectations
• The need to reduce pollution, sewer overflows and leakage
• Rising demand and public scrutiny

Water companies will invest heavily in sewer upgrades, pollution reduction, resilience projects and new technologies to meet national goals.

Read our best practice article on AMP8 and phosphate in water >

Engineers working in water and wastewater must consider:

• Water Industry Act 1991 - defines responsibilities for sewerage undertakers and drainage obligations.
• Environment Act 2021 - drives environmental improvements and statutory obligations such as Drainage & Wastewater Management Plans (DWMPs).
• Regulatory frameworks under Ofwat and AMP cycles - set performance, funding and environmental standards.
• Environmental standards relating to pollution, discharge quality and sewer overflow reduction.

These frameworks guide how water companies plan, build and operate their assets safely and sustainably.

Confined spaces such as tanks, silos and enclosed chambers present unique risks, including:

• Low oxygen or build‑up of toxic gases like H₂S
• Limited ventilation and restricted escape routes
• Higher exposure to fumes, aerosols and biological hazards
• Increased heat stress and physical strain

These conditions require specialist ventilation, continuous gas monitoring, rescue planning and trained confined‑space entry procedures to maintain safety. Confined‑space hazards are particularly relevant in sewage systems and wastewater treatment environments described in statutory wastewater management guidance.