Restrictions limiting the use of tap water in Kuressaare were lifted across most of the city by the Health Board on Thursday after several days of clear tests.
The ban is still enforced around Pikk tänav in the city center as E.coli and three coli-like bacteria were detected in samples. Businesses and residents must continue to boil their tap water before consuming it.
The Health Board's Deputy Director General Mari-Anne Härma said it is essential that people remain vigilant because the fight against bacterial contamination can be a lengthy process.
"The quickest way to get rid of the bacteria is to once again carefully drain the water systems of all establishments and households. Turn on all existing taps and all showers — nothing can be missed," she said.
It is not possible to specify a tap should be left on as it depends on the size of the pipes. For some residences, 10 minutes is enough but for larger properties it could take up to an hour.
Liis Lepik, deputy mayor of Saaremaa, said water company Kuressaare Veevärk is still trying to identify the cause of the pollution. She said the company's risk analysis and operations plan will also be updated.
Residents who have had abdominal complaints should undergo a medical examination before returning to work.
Dr Irina Dontšenko, an adviser at the Health Board, said the bacteria can continue to spread from person to person.
"Therefore, it is very important to follow hygiene rules both when washing hands and handling food — cooking and storing food. You should definitely not go to work when you are ill," she said.
Editor: Merili Nael, Helen Wright