E coli was detected in seven (0.8pc) of public supplies last year, compared with 12 (1.3pc) in 2011.
* The number has reduced from 87 in 2005, representing a 92pc reduction.
* Pesticides were detected in 16 supplies, compared with six the previous year.
* Some 563 number of notifications of VTEC, a strain of e coli, were reported to the HSE in 2012. This compares with 284 the previous year. Part of the increase is due to better testing, while high volumes of rainfall also contributed.
* A total of 339 public supplies needed upgrades in 2008. 237 have been completed.
* The number of public supplies failing to meet standards on trihalomethanes (THMs) rose from 10.9pc to 14.9pc - THMs are a group of chemicals which form when chlorine, used to treat the water, reacts with organic matter. Heavy rainfall and inability of some treatment plants to cope with the problem led to the increase.
* There is concern that water sources are not being protected - 13 of 47 supplies visited had poor source protection.
* Some problems were caused because plants are not being properly managed, particularly in relation to alarms indicating a problem. All staff should be trained.
* Monitoring of e coli in private supplies needs to be improved “as a matter of priority”.