Opening My Pool - How do I fill it?
On the surface filling up your pool after winter and getting ready to open does not seem like a tough thing, and it's not, but you do need to keep a couple things in mind.
Skimmer plug to backfill around pool
First if you have a winter mesh cover and your drain plug was removed for winter to keep the pool from overflowing, you will need to reinstall that plug before filling - or it will not fill. The plug is kept in the bottom of the skimmer loose during winter and simply screws into the 2" threaded hole in the bottom of the skimmer. Simply wrap with Teflon tape and a dab of silicon grease (Magic Lube) and screw it in. If you have a solid auto cover with a cover pump - your pool should have been left at operating level and likely will not need filled back up.
If you have a well at your home we recommend using a 'bobby' or similar hose filter that attaches to your garden hose and filters (at least some of) the sediment, minerals, and metal out of the water before going into the pool. These devices are about $30 and last anywhere from 20,000 to 30,000 gallons of filtering. Keeping those solids out of your pool is an important part of reducing the chance of scaling and maintaining balanced water.
Rain water will work too. If you would like - you can install the plug in the bottom of the skimmer in early spring and let the rain fill the pool. Just make sure the threat of freezing is past before installing the plug and make sure you do it soon enough that you get ample rain to get it up before you want to open.
Water Delivery Truck
Trucking water may also be an option but can also be expensive. In most cases bringing the water level up 4"-6" is as little as 1000 gallons. Since a water truck usually carries 3500-5500 gallons of water you will be buying an entire load for around $200-$300 and using just a fraction of that load. If you have a weak well or a very bad water quality this may be worth it but you will typically have to but the entire load which can be a bit pricey.