lay the mattress inside the waterbed lift up and open the valve if it is a new mattress you will hear air being sucked in as the fiber opens up leave the mattress for a few minutes to allow the mattress to come up to room temperature the fiber to open a little more and the creases in the vinyl to flatten out if the mattress is not centralized you will end up with the tension on one side and slack vinyl and the other it will not be able to move it without emptying it completely so making the effort to centralize the mattress first well ensure the mattress will be filled correctly one corner at a time grip the bottom of the corner seem slightly lift the mattress checking there are no creases in the underside of the vinyl this is normally a problem when a filled mattress has been siphoned these creases needs to be pulled out completely where the mattress will not fit correctly but one corner of the mattress into the corner of the foam surround or hard sided frame make a mental note of whether cooler laid check the next corner the next and the last if one corner was nice and snug into the frame and diagonally opposite corner did not quite fit then the mattress is not perfectly sensible repeat the process several times until you are happy that all the corners are equal you are now ready to fill the mattress you can fill a slightly warm bar and pump the water into the mattress if you have the correct type of pump however it's just as easy to fill using a garden hose always run clean water through whatever hose you use to clear any bacteria ideally connect to a water supply where you can adjust the temperature a mixer tap or shower a perfect hardware stores have those connections that can help or a roll of insulating tape if you can't get the correct fitting never start filling using hot water only as this will damage the vinyl long term newly filled mattress will have more movement than expected for several days as the fiber that has been vacuum packed slowly opens up shake and add the waterbed conditioner remove the air we have a helpful video on how to remove air you will need to do this several times when the mattress is new we also sell crystals that absorb up to 10 liters of air from the water if you find your mattress is producing excessive amounts of air hit the cover on to check the comfort it is useful to have a spare washable top one on the bed and one in the wash see our video adjusting the support of a waterbed mattress