Access to running water is one of those conveniences that are taken for granted. When the water supply is disrupted because of an earthquake or other disaster, or interrupted due to construction work, we realise just how many aspects of our everyday lives are dependent on water, from cleaning and washing clothes, dishes and even ourselves, to preparing food and, of course, for drinking.
The toilet is another place where having running water is vital for maintaining hygiene. But what can you do when you've got to go, but there's no water? Although there are a number of products on the market that help to deal with this issue, here's an inexpensive solution that uses fairly common household items. (If you don't have these, it's a good idea to pick them up to have them on hand.)

What you'll need

• Cardboard box
• Large plastic bags x 2
• Newspaper
• Utility knife

Method

1. Cut a hole in the top of the box to make the toilet seat.

2. Line the box with one plastic bag, pushing the bag into the hole to make the toilet bowl.

3. Place the other bag over the first bag, and place strips of newspaper inside to absorb fluids.

4. After use, add odor remover, and remove the top bag. Remove the air from the bag, tie it closed tightly, and dispose of the bag. Be sure to replace the bag for the next user.

You could also use your home toilet instead of a box, using the first plastic bag to line the bowl, and a second bag as a disposable receptacle.
*Be sure that there are no holes in the bags.

Reference: https://www3.nhk.or.jp/news/contents/bousai_tips/cont16.html