500-Gallon Storage Tank
The 500-Gallon Storage Tank provides 500 gallons of rainwater storage in a polyethylene container measuring 46" diameter x 60" tall. Priced between $300 and $600 ($0.60-$1.20 per gallon of capacity), this tank is a practical mid-range option for homeowners with dedicated irrigation or non-potable indoor needs.
About the 500-Gallon Storage Tank
The 500-gallon polyethylene tank marks the transition from simple rain barrels to serious rainwater storage. At this capacity, you can irrigate a 500-square-foot vegetable garden through a two-week dry spell. These tanks are UV-stabilized, opaque to prevent algae growth, and designed for above-ground installation on a level concrete pad or compacted gravel base. The larger inlet allows connection to multiple downspouts through a distribution manifold, capturing rain from a greater roof area. Most 500-gallon tanks include a 2-inch bulkhead fitting for overflow and a threaded outlet for connecting a garden hose or drip irrigation system. A first-flush diverter is recommended at this scale to improve water quality by discarding the first gallon per 100 square feet of roof during each rain event.
Installation Guide
A 500-gallon tank requires more preparation than a simple rain barrel but is still within reach of experienced DIY homeowners. The most critical step is preparing a proper foundation. When full, this tank weighs approximately 4,170 pounds — that weight must be distributed evenly on a surface that will not shift or settle.
Pour a 4-inch concrete pad extending 6 inches beyond the tank footprint on all sides, or prepare a compacted gravel bed at least 6 inches deep. Ensure the pad is perfectly level using a builder's level. Connect downspouts to the tank inlet using schedule 40 PVC pipe, with a leaf screen or gutter guard at each collection point. Install a first-flush diverter to improve water quality by discarding the first gallon per 100 square feet of roof after each dry period.
Recommended Accessories
- First-flush diverter (1 gallon per 100 sq ft of roof)
- Calmed inlet to reduce sediment disturbance
- Tank-level gauge (float type or electronic)
- Submersible or external pump for pressurized delivery
- Overflow pipe routed to rain garden or storm drain
- Bottom drain valve for annual cleaning
Best Uses for the 500-Gallon Storage Tank
The 500-Gallon Storage Tank serves homeowners with dedicated vegetable gardens (500-2,000 sq ft), drip irrigation systems, lawn watering needs, and indoor non-potable applications like toilet flushing. At 500 gallons, it stores enough water to bridge typical dry periods of 1-3 weeks in most climates. This size is also popular for small livestock operations, greenhouse irrigation, and properties seeking to reduce their municipal water consumption by 30-50%.