You may be able to avoid draining the pool by isolating the plumbing at the pool with properly sized winterizing plugs.

- Turn off power to the pump, including automatic controls.
- Remove the skimmer baskets and plug the pipe openings at the bottom of the skimmers. Covering the skimmer mouths won’t isolate those openings. Use threaded plugs where the fittings accept them, or correctly sized rubber expansion plugs. [Pentair describes using skimmer plugs for winterizing.](https://www.pentair.com/en-us/education-support/water-education-center/pool-and-spa-education/how-to-winterize-a-pool.html)
- Isolate the return lines and any separate main-drain or cleaner lines connected to the plumbing you’re replacing. Equipment below the water level needs isolation on both the suction and return sides. [Pentair pump manual](https://flowandfiltrationsolutions.pentair.com/content/dam/extranet/nam/pentair-pool/residential/pumps/whisperflo-vst/user-guide/whisperflo-vst-install-and-users-guide.pdf)

A separate main-drain line can complicate the job. If a working valve cannot isolate it, have a pool service company handle that part. Before cutting anything, verify through a controlled drain opening that water flow has stopped.

If you need to lower the water, a siphon could save you from needing another pump. Fill a hose completely with water, keep the intake submerged, and put the discharge at a suitable location below the pool’s water surface. Water will flow until the intake draws air or the water levels equalize. A garden hose will work, though it will be slow.

I would avoid cutting a live line and trying to control the flow while attaching temporary plumbing. Install working isolation valves and unions during the repair to make future service easier.

Don’t assume it’s safe to empty the pool completely. Pool construction and groundwater conditions matter, and draining it can damage the shell or liner. [Pentair’s draining caution](https://www.pentair.com/en-us/education-support/water-education-center/pool-after-power-outage.html)