My child wets the bed every night. How can I get this to stop?

Stepwise. Firstly: not your child's fault. Stop fluids after supper and toilet couple of hours after child goes to sleep (if u can). After age 7 try bedwetting alarm, proven best method to cure problem. Alarm is conditioning reflex device so that child will eventually "hear" alarm before after brain detects message that bladder is full and wake or know to hold it. Then medication, ie desmopressin ok 4 use.
Can be normal . Wetting the bed at night can be normal up until age 6 or 7. After this time it is expected that children should be able to go through the night. If your child is older, or used to sleep through the night and now just started wetting the bed try using an alarm which detects moisture and wakes the child up. Then they can get up and go to the bathroom instead of wetting the bed.
Try DDAVP (desmopressin) if 7yr old. A child at least 7yr old, with primary enuresis (meaning he's always been a bed-wetter), can do a trial of DDAVP (desmopressin) tablets, after being seen by a pediatrician to make sure there isn't another medical cause for bed-wetting. Bed-wetting runs in some families, and is a developmental problem that children will outgrow. Ddavp (desmopressin) can reduce or prevent enuresis, while parents wait for a child to mature more.