Arendal municipality is responsible for the operation and maintenance of the municipality ́s water and sewage system (VA), including sewage network, manholes, pump stations and associated technical installations. The procurement is for a water and sewage system in Arendal municipality, as well as drinking water and pumping facilities located in Grimstad municipality. Over time, the municipality has experienced increasing challenges connected to the occurrence of pests, especially rats, in the sewage system. Rat activity in the Water and Sewage network involves a risk of damage to infrastructure and technical installations, ventilating pipes and stuving sewage, pest penetration in buildings, with consequent health and environmental consequences and increased operational costs and a need for acute measures. Risks in particular have been identified connected to the use of technical solutions and traps in the sewage system, where errors or failures can lead to unintended consequences that reinforce the problems, rather than reduce them. There is a need for a system that also ensures inspections. The municipality therefore needs a more uniform and risk based approach to pest control in the Water and Sewage system.