There is no bilateral healthcare provision agreement between the UK and Israel, so travellers to the country need to ensure that they arrange comprehensive medical insurance prior to travel. Medical care in Israel is of a high standard - comparable with the UK and Europe, and is on the whole, quite expensive - almost every treatment needs to be paid for before it will be given and for some severe conditions you would have to be extracted from the country in order to receive treatment elsewhere, so you should ensure that any insurance includes provision for air ambulance within the policy.
Tap water is not always safe to drink, and you should stick to bottled water from a sealed container for your own protection while in the country.
