Sewer blockages are a major cause of sewer flooding. In England and Wales, blockages cause 4,000 property flooding incidents each year. This is around 55% of sewer flooding incidents. The main practice usually used to clear sewer blockages is by employing high pressure (1500 to 5000 psi) water jetting. This is contrary to the practice in mainland Europe where a combination of high volume-low pressure jetting is employed. High pressure water jetting equipment is often used to clean drains and sewers on a regular basis and remove any blockages and sediments from them. However, it has been shown that high pressure water jets can cause damage to the fabric of drains and sewers.

In 2001 a Sewers Jetting Code of Practice was produced by WRc. The code set a number of guidelines, requirements and specifications for use of high pressure jetting. According to the code, concrete pipeline systems currently take a maximum water jetting pressure of 5,000 psi, concrete pipe manufacturers are confident that their products can actually take higher pressure levels. On the other hand, the Code specifies a maximum of 2,600 psi for plastic based pipes. However some water and wastewater companies have their own tougher requirements for maximum jetting pressures in their sewer networks: asking for a maximum of 4,000 psi for plastic pipes. The current situation with maximum jetting pressure is now more complicated with the recent jetting limits set in plastic pipes’ European Standards EN 14654: 2005 and EN 13476: 2007 where a much lower maximum jetting pressure of 120 Bar (around 1740 psi) is specified. This should pose a number of questions on the most appropriate levels of jetting pressure to be used and the actual damage this might cause to specific types of plastic pipeline systems.

Sewer Pipes and Resistance to Jetting This factsheet offers crucial information on water jetting requirements for different sewer pipeline systems, explores the various views and limitations set by different bodies in the industry, and poses a number of questions on the issue.