The curing time for PVC cement (glue) can vary depending on the specific product and brand you are using. Generally, PVC cement does require some time to cure properly before you can turn the water back on. While some products may claim that the joint is "set" or "dry" in as little as 15 minutes, it's important to understand that this does not mean the cement is fully cured and ready for water pressure.
The common recommendation is to wait at least 2 hours before restoring water pressure in the PVC pipes after gluing them together. This ensures that the cement has had sufficient time to bond and create a strong, watertight seal. Waiting for the full curing time will help avoid potential leaks and ensure the joint is as strong as possible.
However, it's essential to follow the manufacturer's instructions on the PVC cement product you are using. Some manufacturers may have different curing times or specific guidelines for their particular product. Always check the label or packaging for the recommended curing time and follow it accordingly to achieve the best results and prevent any issues with your plumbing system.