Contact your local government to see if it offers free water barrels or rebates for purchasing rainwater or gray water harvesting systems. You can usually find this information on the government website or by calling its information line.
Recycled water barrels are often free or very low-cost. Food and beverage distributors are often a good source for these barrels, as are bottling companies. If you are having trouble locating companies, ask the manager of your grocery store which ones were bottled locally. You may have to be able to transport the barrels yourself, so make sure you have access to a large enough vehicle.
Some companies recycle barrels and sell them locally, but those may cost more money. Be careful with barrels that used to contain sweetened foods because they can attract ants.
Free water barrels are often available on local classified advertising sites, such as Craigslist.org. However, be careful with these sources. Try to verify what the barrels used to contain, as they may have held harmful pesticides or other dangerous substances. These chemicals may leave residues that can leach out into your water as it is stored.
Vineyards and breweries are another good source of food-grade water barrels. You can also try car washes, but make sure you wash the barrel thoroughly because car wash barrels are usually used to hold soap.