This is a winner on a hot day and it's cheap!
Use a container, we use under bed storage but we have used washing up bowls in the past.
For the water play we use items from around the home. Daisy loves this and I will often get her to choose things to take outside, like a sieve or straw and cups. You could add food colouring or shampoo to make bubbles as well.
Same with the sand. A bag of play sand is £2.50 from Tesco for 10kg which is a fair amount.
This is a cheap alternative to a sand and water table and my 3 year old loves it.