Using personal guide services if travelling independently, with the exception of resort stays, will save you a great deal of time and money, as the guide will negotiate rates on your behalf, and you won't be constantly hussled by the local service providers and street vendors. If traveling with an escorted Tour be sure to ask your guide for advice on buying. Conservative clothing is the preferred wearing apparel. Although the water is treated, it does contain chemicals that your body will not be used to, and these chemicals won't disappear with boiling. So please be cautious with all drinks and food that may contain water, i.e Coffee, Tea, Ice, etc.
Bottled water is available everywhere, the Baraka brand does have a mild laxative effective.
You can also purchase a filter water bottle to take with you from most Department Stores. Take the usual precautions with meat and fish ensuring it is well cooked and heated, and remove peel from any vegetables or fruits. If you should run into problems the pharmacies carry products that we have found work extremely well and are superior to anything I was able to purchase in North America. It is advisable to take and carry imodium around with you. No immunisations or special Health precautions are normally required for Egypt.