Water Tank Installation Guide

Before You Start — Decisions to Make

Step-by-Step Installation

1. Check permit requirementsCall your county building department. Permits are typically required for tanks over 1,000 gallons, any potable water connection, concrete pads, or fire suppression tanks. Getting a permit protects you at property sale and ensures insurance coverage.
2. Prepare the siteClear vegetation and debris. Grade the area level — a tank on an uneven surface puts stress on the base and can cause distortion or failure under load. For tanks over 250 gallons, ensure vehicle access for the delivery truck (most tanks over 300 gallons won't fit through a standard gate).
3. Build the foundation padUnder 500 gallons: 4"–6" of compacted crushed gravel or road base, extended 6" beyond the tank footprint on all sides. 500–2,500 gallons: 4" reinforced concrete pad, sized to tank footprint + 12". Over 2,500 gallons: consult a structural engineer — load calculations are needed. Key requirement: completely flat and level. Check with a level in two directions before pouring or before final gravel compaction.
4. Install bulkhead fittings before positioningInstall all fittings in the tank before it's in final position — it's much easier to work on a tank you can move. Install: fill inlet fitting (top of tank), primary outlet fitting (near bottom, with a ball valve), secondary outlet or drain (very bottom, for complete drainage), and overflow fitting (at the 95–100% full line). Use NSF-61 poly bulkhead fittings and thread sealant tape on all threads.
5. Position the tankTanks over 300 gallons require equipment. Do NOT drag the tank — dragging scratches and stresses the base. Use a forklift, loader bucket, or crane depending on size. Set slowly and carefully onto the prepared pad. Check level after setting — shim with thin gravel if needed before the pad is finished.
6. Plumb the inlet supply lineRun supply pipe (PVC or poly pipe) from your water source to the fill inlet fitting. Install a float valve in the tank or a solenoid valve on the supply line if you want automatic fill. Install a backflow preventer between the municipal supply and the tank if required by local code (required in most jurisdictions for cross-connection protection).
7. Plumb the outlet and distribution linesRun outlet pipe from the primary outlet ball valve to your distribution point (pump, gravity-fed header, or irrigation manifold). Install a sediment filter at the outlet if supplying potable water. For gravity-fed systems, elevate the tank as high as practical — every 2.3 feet of elevation = approximately 1 PSI of pressure.
8. Install the overflow lineRoute the overflow fitting to a safe discharge point — a French drain, infiltration area, or collection point. Never route overflow to a location that could cause erosion, flooding, or property damage. Overflow should be sized at least as large as the inlet line.
9. Install pump and pressure system (if needed)For household pressure: install a submersible pump inside the tank or a jet pump at the outlet, plus a pressure tank (2–5 gallon minimum for residential) to reduce pump cycling. Set the pressure switch to 30–50 PSI for typical household use. For irrigation-only: a booster pump sized to your GPM requirement is sufficient.
10. First fill and inspectionFill slowly for the first fill. Walk around the tank at 25%, 50%, and 75% capacity to inspect for leaks at all fittings. Check the overflow level. Confirm the pump operates correctly at target pressure. For potable water: sanitize the tank before use — see your tank manufacturer's instructions, typically a dilute bleach flush.

Foundation Sizing Reference

Permits — What You Need to Know

Permit requirements vary significantly by county and state, but the following typically trigger a permit requirement:

• Tanks over 1,000 gallons in most jurisdictions
• Any connection to a potable (drinking) water supply system
• Tanks on a permanent concrete pad (treated as a structure)
• Fire suppression tanks (always require permits and NFPA 22 compliance)
• Rainwater harvesting systems in states that regulate it (check state law)
• Tanks within setback distances from property lines, wells, or septic systems

To check your requirements: call your county planning or building department and ask specifically about "above-ground water storage tanks." Have your tank size, intended use (potable/non-potable), and installation location ready. In rural agricultural counties, small farm tanks are often exempt — but don't assume.

Written by

Lawrence

Water and wastewater treatment professional with 18+ years of hands-on industry experience. Grade IV Wastewater Certification holder. Founded TankAuthority to bring real operator knowledge to water storage decisions.