Pure water is neutral. if water is neither an acid nor base what is the ph of the water

The answer is 7.

Since pH values are made up of 14 numbers, and the smaller the number is, the more acidic a substance is, and the larger the pH value is, the more alkaline the substance is. So, the median number of the pH scale is 7. 

We can easily test the pH value of simple substances (liquid the best) by using pH paper, which you can easily get in drugstores, or pH meter, where you should be able to find in most laboratories. You'll have a chart to match with and you should get the value of 7 if it's pure water that you're testing. 

Its pH is constant which is neither acid or base