I run a line pump, and was wondering if there is a waiver or something that you have the customer sign, in case of splatter on the house, or problems that dont apply to me. Just a CYA.

look at the RM ticket that states no liability back of curb deliveries. make it clear that you do not provide certificates of insurance after service is provided. all deals are done in advance if they have some expectation of you providing insurance on their project for being there for a couple hours. RM tuck point of delivery is your pump and the driver and the water is yours, third parties giving the RM driver instuctions is not aceptable. if you drive away unpaid have a signed time acceptance. the clowns that clean your carpets have you sign work orders even if they sell you air freshner for twenty bucks. 

Make up what ever you want it to say and have the customer sign it before you start.

Liability waivers are, in many cases, useless. Most states don't allow anyone to sign away their rights to sue for negligence. In spite of what you may put on a waiver of liability, state laws will trump your signed WoL. Best advice will come from an attorney well versed in your home state's liability laws, not an internet message board.