Residential Water Storage and Rainwater Harvesting: Tank Selection and Installation Guide
Residential Water Storage and Rainwater Harvesting
Whether you are building a rainwater collection system, maintaining emergency water reserves, or supplementing a well with stored water, residential water storage requires food-grade polyethylene tanks rated for potable water contact. The FDA approval (21 CFR 177.1520) ensures the resin won't leach chemicals into your drinking water. Black or dark-colored tanks are preferred for outdoor water storage because they block sunlight, which prevents algae growth.
Why Tank Selection Matters for Residential Water Storage and Rainwater Harvesting
Not every polyethylene tank works for every application. The wrong tank can mean chemical incompatibility, premature failure, regulatory violations, or simply wasted money on features you don't need. This guide walks you through the specific requirements for residential water storage and rainwater harvesting and matches you with the right tank from our catalog.
Key Requirements
- FDA Approval — Required for any tank that will hold drinking water. Look for tanks specifically marked FDA approved.
- Algae Prevention — Dark tank colors (black, dark green) block sunlight. Clear and white tanks promote algae growth.
- Overflow and First-Flush — Rainwater systems need overflow piping and ideally a first-flush diverter to discard roof contaminants.
- Filtration — Municipal backup water can go directly into a food-grade tank. Rainwater needs filtration and potentially UV treatment.
Recommended Tank Types
Vertical Water Storage
Standard above-ground water tanks in black for algae prevention. SG 1.0-1.1 rated — water only.
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Doorway Tanks
Narrow-profile tanks that fit through standard doorways for indoor/basement water storage.
Shop Doorway Tanks
Installation Considerations for Residential Water Storage and Rainwater Harvesting
Local Regulations
Rainwater harvesting laws vary by state. Most states now allow residential collection, but some have restrictions on tank size, placement, or intended use. Potable water tanks connected to plumbing may require backflow prevention and health department approval.
Foundation and Placement
Water is heavy — 8.34 pounds per gallon. A 1,000-gallon tank holds over 8,300 pounds of water. Place on a concrete pad or compacted gravel base rated for the full loaded weight.
Sizing Your Tank
Tank sizing for residential water storage and rainwater harvesting depends on your usage rate, refill frequency, and peak demand. The general formula is:
Required Capacity = Daily Usage × Days Between Refills × 1.2 Safety Factor
The 1.2 safety factor accounts for peak usage days, delivery delays, and the fact that you should never run a tank completely dry (the sediment at the bottom can clog fittings and pumps). If your application has seasonal peaks, size for peak demand rather than average demand.
Maintenance Specific to Residential Water Storage and Rainwater Harvesting
Standard polyethylene tank maintenance applies: quarterly visual inspection, fitting checks, foundation verification, and vent maintenance. For residential water storage and rainwater harvesting specifically, pay extra attention to:
- Chemical compatibility: If you change chemicals or suppliers, verify the new formulation is compatible with polyethylene and within the tank's specific gravity rating before adding it to the tank.
- Residue buildup: Some liquids leave residue on tank walls over time. Annual interior inspection and cleaning prevents buildup from affecting liquid quality or reducing effective capacity.
- Fitting condition: Applications with frequent connect/disconnect cycles wear fittings faster. Replace threaded fittings at the first sign of thread damage — a cross-threaded or stripped fitting is a leak waiting to happen.
- Secondary containment: If required by your local regulations, inspect containment berms, dikes, or trays during each tank inspection. Secondary containment only works if it's intact.
Frequently Asked Questions
What size tank do I need for residential water storage and rainwater harvesting?
Start with your daily usage rate and multiply by the number of days between refills, then add 20% for safety margin. For example, if you use 50 gallons per day and refill weekly, you need: 50 × 7 × 1.2 = 420 gallons minimum. Round up to the next standard size — in this case, 500 gallons.
Do I need a chemical-rated tank or a water-only tank?
If you are storing anything other than clean water, choose a chemical-rated tank (SG 1.5 or higher). The thicker walls and higher material rating provide safety margin for chemical exposure, and you won't need to replace the tank if you switch liquids later. Water-only tanks save money but limit your future options.
What permits do I need?
Permit requirements depend on your location, the tank size, and what you are storing. Water storage typically requires no permits below 5,000 gallons. Chemical storage often requires permits, secondary containment, and fire marshal review. Agricultural exemptions may apply for farm chemical storage. Always check with your local building department and fire authority before installation.
Can I install the tank myself?
For tanks under 500 gallons, DIY installation is straightforward if you follow proper site preparation and plumbing practices. For larger tanks, we recommend professional installation — the weight involved creates safety risks, and improper placement can void the warranty. Either way, a proper foundation is non-negotiable.
How do I handle delivery and placement?
Small tanks (under 200 gallons) ship via UPS/FedEx ground. Mid-size tanks (200-1000 gallons) ship LTL on a pallet — you'll need a forklift or request liftgate delivery. Large tanks (1000+ gallons) ship via flatbed and require equipment for unloading. Call us to coordinate delivery logistics for your specific site conditions.
Need expert guidance on tank selection for residential water storage and rainwater harvesting? Call (866) 418-1777 — we'll help you size, select, and plan your installation.