The cleaning and treatment of fresh water and sewage is associated with hazards just as much as the maintenance of the sewage system itself.

The presence of toxic or flammable gases and oxygen deficiencies are a potential risk. There are specific risks to staff and facilities in each stage of the water recovery and treatment process, which includes toxic gases, flammable gases and low oxygen levels.

Working on water or sewage channels still requires manual visual inspection, fixing faults, maintenance and cleaning. A lack of ventilation combined with biological fermentation processes and chemical reactions encourage the accumulation of methane (CH₄) or even hydrogen sulphide (H₂S) at critical concentrations. CH₄ is extremely flammable and can react explosively. Even at very low concentrations, H₂S is extremely toxic to the human body.

Furthermore, the use of ammonia and chlorine for water treatment is derived from a highly noxious gas which, even in the smallest quantities, is harmful to the respiratory system. Fire and gas mapping assessment can act as an assurance mechanism to ensure the early leak detection systems are designed to meet the highest safety standards.