SC By SCWS Team | January 18, 2026 | 9 min read
Steel vs Fiberglass Pressure Tank: Which Is Better?
Time to replace your well pressure tank? You'll face a choice between traditional steel and modern fiberglass (composite) tanks. Both do the same job—storing pressurized water to reduce pump cycling—but they have important differences in durability, weight, cost, and longevity. Here's how to choose the right material for your situation.
⚡ Quick Answer
Fiberglass tanks are the better choice for most wells—they're corrosion-proof, lighter, and typically last longer. Steel tanks remain a solid budget option for dry climates and controlled environments where rust isn't a concern.
Understanding Pressure Tanks
Before comparing materials, let's understand what pressure tanks do and why the outer shell matters.
How Pressure Tanks Work
Modern well pressure tanks use a bladder or diaphragm to separate water from compressed air. When your pump fills the tank, water enters the bladder and compresses the air behind it. This stored pressure:
- Delivers water to your fixtures when the pump isn't running
- Reduces pump cycling (extending pump life)
- Maintains consistent water pressure throughout your home
- Provides a buffer during peak demand periods
The tank shell—whether steel or fiberglass—contains this pressure and protects the internal components. For a deeper dive, see our guide on how well pressure tanks work.
What Matters in a Pressure Tank
- Drawdown capacity: How much water can be used before the pump kicks on
- Pressure rating: Maximum operating pressure (typically 100-150 PSI)
- Bladder quality: The component most likely to fail
- Shell durability: Resistance to corrosion, damage, and environmental factors
- Size/footprint: Physical dimensions matter in tight pump houses
Steel Pressure Tanks
Steel has been the standard pressure tank material for decades. Quality steel tanks from manufacturers like Well-X-Trol, Amtrol, and Flexcon have proven track records.
Steel Tank Construction
Steel pressure tanks typically feature:
- Rolled and welded steel shell
- Interior epoxy or powder coating to protect against water contact
- Exterior paint or primer for rust protection
- Heavy-duty butyl rubber or EPDM bladder
- Stainless steel or brass fittings
Steel Tank Advantages
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Lower upfront cost: 20-40% less than equivalent fiberglass
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Proven technology: Decades of track record
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Wide availability: Stocked at most plumbing suppliers
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Impact resistant: Less prone to cracking from physical damage
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Many size options: Available in nearly any capacity
Steel Tank Disadvantages
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Prone to rust: External corrosion in humid environments
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Heavier: Makes installation and replacement more difficult
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Shorter lifespan: Often 10-15 years vs. 15-25 for fiberglass
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Iron water issues: Rust stains and accelerated corrosion
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Coating deterioration: Interior coating can fail over time
Fiberglass (Composite) Pressure Tanks
Fiberglass pressure tanks—also called composite or FRP (fiber-reinforced plastic) tanks—represent the modern evolution of pressure tank technology.
Fiberglass Tank Construction
Fiberglass pressure tanks feature:
- Wound fiberglass shell with resin matrix
- No interior coating needed (fiberglass doesn't corrode)
- UV-resistant exterior gel coat
- Same high-quality butyl/EPDM bladders as steel tanks
- Stainless steel or composite fittings
Fiberglass Tank Advantages
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Corrosion-proof: Cannot rust, inside or out
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Lightweight: 40-60% lighter than equivalent steel
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Longer lifespan: Typically 15-25 years
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Better for challenging water: Iron, sulfur, acidic water
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No interior coating: Nothing to chip or degrade
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Easier installation: One-person installation possible
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Better insulation: Less temperature transfer
Fiberglass Tank Disadvantages
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Higher upfront cost: 20-40% more than steel
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Less impact resistant: Can crack from sharp impacts
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Limited availability: Some sizes may need ordering
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UV sensitivity: Must protect from prolonged sun exposure
📊 Side-by-Side Comparison
| Factor | Steel Tank | Fiberglass Tank |
|---|---|---|
| Typical Lifespan | 10-15 years | 15-25 years |
| Corrosion Resistance | Prone to rust | Corrosion-proof |
| Weight (85 gal) | ~120 lbs empty | ~50 lbs empty |
| Cost (85 gal) | $400-$600 | $500-$800 |
| Impact Resistance | Excellent | Good (avoid sharp impacts) |
| Iron Water Performance | Accelerated wear | No effect |
| Installation Ease | Requires 2 people | 1 person possible |
| Availability | Widely stocked | May need ordering |
Cost Comparison
Purchase Price by Size
| Tank Size | Steel Price | Fiberglass Price | Difference |
|---|---|---|---|
| 20 gallon | $150-$200 | $200-$280 | +$50-$80 |
| 44 gallon | $250-$350 | $320-$450 | +$70-$100 |
| 85 gallon | $400-$600 | $500-$800 | +$100-$200 |
| 119 gallon | $600-$900 | $800-$1,200 | +$200-$300 |
Total Cost of Ownership (20 Years)
When you factor in lifespan differences, the picture changes:
Steel Tank (85 gal)
$1,200-$1,800
- • Initial cost: $500 (avg)
- • Replacement at year 12: $550 (avg)
- • Installation (2x): $300
- • 20-year total: 2 tanks
Fiberglass Tank (85 gal)
$800-$1,000
- • Initial cost: $650 (avg)
- • No replacement needed
- • Installation (1x): $150
- • 20-year total: 1 tank
The higher upfront cost of fiberglass is often recovered through longer lifespan. See our complete pressure tank replacement cost guide for detailed pricing.
Environmental Factors
When Steel Performs Well
- Dry climates: Low humidity reduces rust risk (inland San Diego County)
- Climate-controlled spaces: Inside heated/cooled pump rooms
- Clean water: Low iron, near-neutral pH, no corrosive elements
- Protected locations: Away from irrigation spray and rain exposure
When Fiberglass Excels
- Humid environments: Coastal areas, unvented pump houses
- Challenging water quality: Iron, sulfur, low pH, mineral content
- Outdoor installations: Better UV resistance than bare steel
- Tight spaces: Lighter weight allows maneuvering
- Retrofits: Easier to bring through doorways and install
📍 San Diego County Considerations
Coastal properties and areas with morning marine layer exposure are particularly hard on steel tanks. Inland areas like Ramona, Julian, and Alpine can go either way—assess your pump house humidity levels. Iron-rich water (common in much of the county) favors fiberglass regardless of location.
Quality Brands to Consider
Quality Steel Tank Manufacturers
Well-X-Trol (Amtrol)
Industry standard, excellent bladder quality, wide availability. 5-year manufacturer warranty.
Flexcon Industries
Heavy-gauge steel, superior coatings, American-made. Known for durability.
Quality Fiberglass Tank Manufacturers
Wellmate (Pentair)
Most popular fiberglass brand, proven reliability, excellent warranty. Our most recommended option.
Flexcon FL Series
Quality composite construction, competitive pricing, good availability.
💡 Pro Tip: Focus on Bladder Quality
The bladder usually fails before the shell on quality tanks. Regardless of shell material, choose brands known for high-quality butyl or EPDM bladders. A great shell with a cheap bladder will still fail early.
Making the Right Choice
✅ Choose Fiberglass If:
- • Your water has iron, sulfur, or other corrosive elements
- • Your pump house is humid or poorly ventilated
- • You're in a coastal area or subject to marine layer
- • You want the longest possible lifespan
- • You're doing a one-person installation
- • You prefer the "buy once" approach
✅ Choose Steel If:
- • Budget is your primary constraint
- • Your pump house is dry and climate-controlled
- • Your water quality is good (low iron, neutral pH)
- • You're in a dry inland area
- • The tank location risks physical impacts
- • You need immediate availability
Frequently Asked Questions
What's the main difference between steel and fiberglass pressure tanks?
Steel tanks are heavier, more traditional, and prone to rust but often less expensive. Fiberglass (composite) tanks are lighter, corrosion-proof, and typically last longer but cost more upfront. Both use internal bladders to separate water from air—the shell material is the key difference.
Which pressure tank material lasts longer?
Fiberglass tanks typically last 15-25 years, while steel tanks average 10-15 years. Steel tanks can fail sooner in humid environments or with corrosive water due to rust. The bladder inside either tank type usually lasts 5-10 years and can sometimes be replaced separately.
How much does a fiberglass pressure tank cost compared to steel?
Fiberglass tanks typically cost 20-40% more than equivalent steel tanks. A quality 85-gallon steel tank runs $400-$600, while a comparable fiberglass tank costs $500-$800. However, the longer lifespan often makes fiberglass cheaper over time.
Is a fiberglass pressure tank better for well water with iron?
Yes. Iron-rich water accelerates rust on steel tank exteriors (especially in humid pump houses) and can stain the tank. Fiberglass tanks are completely immune to rust and iron staining. If your well has iron issues, fiberglass is the better long-term choice.
Are steel pressure tanks still a good choice?
Yes, quality steel tanks remain a solid choice for many installations—especially in dry climates, climate-controlled spaces, or budget-conscious projects. Major brands like Amtrol, Flexcon, and Well-X-Trol make durable steel tanks that can last 15+ years in good conditions.
Can I install a larger pressure tank to reduce pump cycling?
Yes, larger tanks (more drawdown capacity) allow the pump to run longer but less frequently, reducing wear. A larger tank is often a better investment than replacing a failed smaller tank with the same size. The material matters less than getting adequate capacity for your household's demand.
How can I tell if my pressure tank is failing?
Signs include: pump cycling rapidly (every few seconds), waterlogged tank (very heavy, can't maintain pressure), visible rust or corrosion on steel tanks, fluctuating pressure at fixtures, or hissing sounds indicating air leaks. Check tank pressure with the system off—it should match the cut-in pressure minus 2 PSI.
Do fiberglass tanks work in cold climates?
Yes, fiberglass performs well in cold climates and is actually less prone to freeze damage than steel (fiberglass has some flex). However, all pressure tanks should be protected from freezing. If installed outdoors or in unheated spaces, proper insulation and freeze protection are essential.
Need a Pressure Tank Replacement?
We install both steel and fiberglass pressure tanks and can recommend the best option for your specific situation, water quality, and environment. We also properly size tanks to reduce pump cycling and extend system life.
