This process is called an inspection and is usually carried out by trained professional using a small CCTV camera that is remotely driven through the pipe, capturing video footage of the internal condition of the pipe as it goes. The best practice is to undertake these inspections at a frequency of around once every 10 years, equivalent to inspecting 10% of the network every year. This frequency means that it would take the relevant water authority 10 years to get around to the same pipe if it were to continuously inspect their pipe network. Water authorities are inspecting their network continuously, but not at the ‘best practice’ frequency of once every 10 years. The frequency at which pipes are inspected differs based on the water authorities’ budgets and the risk of that asset’s failure to the community and environment. In some areas and countries, it is common for pipes to be assessed at a much lower frequency i.e. Inspected at less than 10% of the network every year. In the United States, almost 7% (source: https://www3.epa.gov/npdes/pubs/sewcl.pdf) of the network is inspected each year, but other countries like the United Kingdom and Australia (based on anecdotal industry experience) is less than 5%.