H2O

When I came to Cairo, I discovered tap water here is quite evil. The first few times taking a shower I thought I was being intoxinated by the smell of bleach.
Take a bath, empty half of your bottle showergel in it and look!, after 5 minutes all your bubbles are gone. Need I say more that it is not advisable to drink from the tap here in Cairo. They say boiled tapwater is fine, so you can use it for cooking. I am quite extreme and think this water is overchlorinated and don't want my lovely food to soak up that horrible taste.

You can find some good tasty water here, there is a variety of choice. Just be sure to read the label on the bottle to see how much TDS (Total Dissolved Salt) is contained. If the level is more than 200, do not buy it. That level is too high. To be safe, stick to water that has the least TDS as much as possible. Dasani for example has a TDS of 16o. Aqua has 272 (better not to drink too much of that) and Siwa 197 (just on the edge)

The prices of water vary a little, but they more or less cost the same, with the difference of a few pounds. The last time, in June when I ordered a box of Aquafina I paid 24 pounds a box. Dasani and Nestle are almost the same price I think. Siwa is a little cheaper. Today I did my first order with them. So straight from their store and not through a supermarket.
One box of Siwa: 20 LE. Delivery costs: none. Their number: 19409 (they speak reasonable English!) Order was done this morning and they came after 20.00 (because of course....Ramadan) I am not sure how long it normally takes them. They didn't charge me for the delivery, I don't know if that is normally the case (I ordered ten boxes).

Metro (19619) and Alfa (19299) of course also deliver water, check with them which brands. They have a small delivery charge (I think around 4 pounds). The small local supermarkets usually don't charge for delivery, but involve some Arabic skills and of course don't foget the baksheesh(tip) ...!