Iran is generally a very safe and secure place to travel, so much so that many tourists describe it as the ‘safest country I’ve ever traveled to’, or ‘much safer than travelling in Europe’. You might have read a lot about Iran on the Internet and got worried but I really advise you to read the tourists personal weblogs and diaries, too.
The truth is that Iranian people are so warm and hospitable that every tourist and foreigner would admit it after the journey is done. Men and women, by tours or even alone, are treated with respect. In fact people are so kind that invite the tourists to their home and try their best to prove that hospitality is in Iranian's gene.
Violent crime against foreigners is particularly rare and, indeed, if you do your best to get on well with local customs, you are unlikely to be treated with anything but politeness and friendliness – that applies to Americans and British, too. You can get a ride across deserts, stayed in the homes of strangers and left bags in restaurants and cafes without any problem.
While traveling by metro, you can see that men and women are separated that means females can easily get to their destination at any time without being worried and it is another reason for safety and security of Iran.
Tap water is safe to drink in most of the country (and especially the cities), although you may find the chalkiness taste or disgusting in some areas (mainly Qom, Yazd, Hormozgan and Boushehr provinces).But there is nothing to be worried about because mineral water is extensively available. You can also find public water fridges installed on streets to provide drinking water.
In case of emergency, you can call 110, the police number with an English speaker operator is at your service.
In general, Iranian people are heartfelt, friendly and generous individuals with a strong interest in foreigners and other cultures and Iran is a very safe place with a great history that you shouldn't miss it.