While your liability insurance may cover you if you damage someone else’s property while using the hired kit (eg. you swing the bucket into the side of their house), it may not cover damage to or theft of the equipment itself. And depending what your hire contract is you could be liable for all sorts of things.
On another note, if you own your own stuff and are hiring it out to other businesses you need to make sure that the insurance for that equipment allows “dry hire”. Otherwise, it may not be covered if something happens while it’s hired out.