Top Mount FRP Tanks - 2.5" NPSM Series
Top Mount FRP Tanks - 2.5" NPSM Series
This is our core series of high-performance FRP tanks, all featuring a standard 2.5" NPSM threaded top opening. These tanks are the industry-leading choice for residential and light commercial water softeners, media filters, and carbon filters that use 2.5" control valves.
This is our core series of high-performance FRP tanks, all featuring a standard 2.5" NPSM threaded top opening. These tanks are the industry-leading choice for residential and light commercial water softeners, media filters, and carbon filters that use 2.5" control valves.
The Foundation for Every Reliable Water Softener System
As a system installer, OEM, or distributor, you know that the tank is the heart of any water treatment system. You need a product that is 100% reliable, installs easily, and is compatible with the valves you trust. This is that product.
The Stark Water 2.5" NPSM Series is the industry's workhorse, precision-engineered to serve as the foundation for residential and light commercial water softeners, media filters, and carbon filters. We designed this series specifically for professionals who demand quality and consistency.
Why Professionals Choose Our 2.5" NPSM Tanks
Your reputation is built on the systems you install. Here is why our tanks are the preferred choice for B2B professionals:
- Perfect Valve Compatibility (The 2.5" Standard)
The most critical component is the connection. Our precision-molded 2.5" NPSM threaded opening provides a perfect, leak-proof seal with all major control valves, including **Clack, Fleck, and Runxin**. This precision manufacturing prevents costly cross-threading and saves you time on installation. - 100% Corrosion-Proof Construction
Forget rust. Our tanks feature a one-piece, seamless high-density polyethylene (HDPE) inner liner. This food-grade liner is then wound with high-strength fiberglass and sealed with epoxy resin. The result? A tank that is 100% corrosion-proof and waterproof, ensuring a long, maintenance-free life. - Engineered for Unmatched Durability & Trust
Your customers trust you. You can trust our tanks. Every tank:- Is rated for 150 PSI (10 bar) operating pressure.
- Has passed rigorous 300,000+ cycle testing without failure.
- Is 100% factory pressure-tested before shipping.
- (Optional, but critical if you have it: Is NSF/ANSI 44 Certified for material safety and structural integrity.)
- Lightweight & Easy to Install
Unlike heavy, rust-prone steel tanks, our composite tanks are lightweight and easy for a single technician to handle (on most residential sizes). This reduces fatigue, speeds up installation, and lowers your labor costs.
Who is this series for?
This 2.5" series is the ideal choice for:
- Water Softener Installers & Plumbers
- Residential & Commercial Water Treatment OEMs
- Well Water System Specialists
- Distributors of Water Filtration Components
Need a Different Opening Size?
This page details all our 2.5" NPSM models. For other configurations, please see our other series:
Below are the full specifications for our 2.5" NPSM top-mount series. Find your required model by US Gallons (Gal) or Liters (L), and US standard dimensions (Inches) or Metric (mm). Click "Request a Quote" for fast, accurate B2B pricing.
| Model | Volume | Nominal Dimensions | Flow Rate (m³/h) | Request a Quote | ||
|---|---|---|---|---|---|---|
| US (Gal) | Metric (L) | US (in) (D x H) | Metric (mm) (D x H) | (Filter/Softener) | ||
| STK-713 | 1.0 | 3.6 | 7" x 13" | Ø188 x 335 | 0.3-0.7 | Inquiry |
| STK-717 | 1.3 | 5 | 7" x 17" | Ø188 x 430 | 0.3-0.7 | Inquiry |
| STK-735 | 2.9 | 11 | 8" x 35" | Ø205 x 905 | 0.3-0.7 | Inquiry |
| STK-835 | 4.5 | 17 | 8" x 44" | Ø205 x 1130 | 0.3-0.7 | Inquiry |
| STK-835 (alt) | 5.8 | 22 | 9" x 35" | Ø230 x 905 | 0.5-1.2 | Inquiry |
| STK-942 | 7.1 | 27 | 9" x 42" | Ø230 x 1085 | 0.5-1.2 | Inquiry |
| STK-948 | 7.9 | 30 | 9" x 48" | Ø230 x 1230 | 0.5-1.2 | Inquiry |
| STK-1017 | 3.2 | 12 | 10" x 17" | Ø255 x 445 | 0.8-1.4 | Inquiry |
| STK-1035 | 7.1 | 27 | 10" x 35" | Ø255 x 905 | 0.8-1.4 | Inquiry |
| STK-1044 | 9.0 | 34 | 10" x 44" | Ø255 x 1130 | 0.8-1.4 | Inquiry |
| STK-1054 | 11.4 | 43 | 10" x 54" | Ø255 x 1390 | 0.8-1.4 | Inquiry |
| STK-1252 | 15.3 | 58 | 12" x 52" | Ø300 x 1340 | 0.8-1.5 | Inquiry |
| STK-1265 | 19.3 | 73 | 12" x 65" | Ø300 x 1650 | 0.8-1.5 | Inquiry |
| STK-1354 | 18.8 | 71 | 13" x 54" | Ø330 x 1400 | 1.2-2.3 | Inquiry |
| STK-1465 | 26.2 | 99 | 14" x 65" | Ø355 x 1670 | 1.2-2.3 | Inquiry |
| STK-1665 | 26.2 | 99 | 16" x 65" | Ø400 x 1670 | 1.2-2.3 | Inquiry |
*Note: US dimensions (inches) are nominal. Please refer to metric dimensions (mm) for exact engineering specifications. Flow rates are estimates; consult our engineers for system design verification.
- Residential Water Softeners
- Residential Well Water Treatment
- Light Commercial Water Softeners
- Point-of-Entry (POE) Filtration Systems
- Activated Carbon Filters
- Media Filters (e.g., Birm, Greensand)
- Sediment Filtration
- Small RO System Pre-treatment
The Foundation for Every Reliable Water Softener System
As a system installer, OEM, or distributor, you know that the tank is the heart of any water treatment system. You need a product that is 100% reliable, installs easily, and is compatible with the valves you trust. This is that product.
The Stark Water 2.5" NPSM Series is the industry's workhorse, precision-engineered to serve as the foundation for residential and light commercial water softeners, media filters, and carbon filters. We designed this series specifically for professionals who demand quality and consistency.
Why Professionals Choose Our 2.5" NPSM Tanks
Your reputation is built on the systems you install. Here is why our tanks are the preferred choice for B2B professionals:
- Perfect Valve Compatibility (The 2.5" Standard)
The most critical component is the connection. Our precision-molded 2.5" NPSM threaded opening provides a perfect, leak-proof seal with all major control valves, including **Clack, Fleck, and Runxin**. This precision manufacturing prevents costly cross-threading and saves you time on installation. - 100% Corrosion-Proof Construction
Forget rust. Our tanks feature a one-piece, seamless high-density polyethylene (HDPE) inner liner. This food-grade liner is then wound with high-strength fiberglass and sealed with epoxy resin. The result? A tank that is 100% corrosion-proof and waterproof, ensuring a long, maintenance-free life. - Engineered for Unmatched Durability & Trust
Your customers trust you. You can trust our tanks. Every tank:- Is rated for 150 PSI (10 bar) operating pressure.
- Has passed rigorous 300,000+ cycle testing without failure.
- Is 100% factory pressure-tested before shipping.
- (Optional, but critical if you have it: Is NSF/ANSI 44 Certified for material safety and structural integrity.)
- Lightweight & Easy to Install
Unlike heavy, rust-prone steel tanks, our composite tanks are lightweight and easy for a single technician to handle (on most residential sizes). This reduces fatigue, speeds up installation, and lowers your labor costs.
Who is this series for?
This 2.5" series is the ideal choice for:
- Water Softener Installers & Plumbers
- Residential & Commercial Water Treatment OEMs
- Well Water System Specialists
- Distributors of Water Filtration Components
Need a Different Opening Size?
This page details all our 2.5" NPSM models. For other configurations, please see our other series:
Below are the full specifications for our 2.5" NPSM top-mount series. Find your required model by US Gallons (Gal) or Liters (L), and US standard dimensions (Inches) or Metric (mm). Click "Request a Quote" for fast, accurate B2B pricing.
| Model | Volume | Nominal Dimensions | Flow Rate (m³/h) | Request a Quote | ||
|---|---|---|---|---|---|---|
| US (Gal) | Metric (L) | US (in) (D x H) | Metric (mm) (D x H) | (Filter/Softener) | ||
| STK-713 | 1.0 | 3.6 | 7" x 13" | Ø188 x 335 | 0.3-0.7 | Inquiry |
| STK-717 | 1.3 | 5 | 7" x 17" | Ø188 x 430 | 0.3-0.7 | Inquiry |
| STK-735 | 2.9 | 11 | 8" x 35" | Ø205 x 905 | 0.3-0.7 | Inquiry |
| STK-835 | 4.5 | 17 | 8" x 44" | Ø205 x 1130 | 0.3-0.7 | Inquiry |
| STK-835 (alt) | 5.8 | 22 | 9" x 35" | Ø230 x 905 | 0.5-1.2 | Inquiry |
| STK-942 | 7.1 | 27 | 9" x 42" | Ø230 x 1085 | 0.5-1.2 | Inquiry |
| STK-948 | 7.9 | 30 | 9" x 48" | Ø230 x 1230 | 0.5-1.2 | Inquiry |
| STK-1017 | 3.2 | 12 | 10" x 17" | Ø255 x 445 | 0.8-1.4 | Inquiry |
| STK-1035 | 7.1 | 27 | 10" x 35" | Ø255 x 905 | 0.8-1.4 | Inquiry |
| STK-1044 | 9.0 | 34 | 10" x 44" | Ø255 x 1130 | 0.8-1.4 | Inquiry |
| STK-1054 | 11.4 | 43 | 10" x 54" | Ø255 x 1390 | 0.8-1.4 | Inquiry |
| STK-1252 | 15.3 | 58 | 12" x 52" | Ø300 x 1340 | 0.8-1.5 | Inquiry |
| STK-1265 | 19.3 | 73 | 12" x 65" | Ø300 x 1650 | 0.8-1.5 | Inquiry |
| STK-1354 | 18.8 | 71 | 13" x 54" | Ø330 x 1400 | 1.2-2.3 | Inquiry |
| STK-1465 | 26.2 | 99 | 14" x 65" | Ø355 x 1670 | 1.2-2.3 | Inquiry |
| STK-1665 | 26.2 | 99 | 16" x 65" | Ø400 x 1670 | 1.2-2.3 | Inquiry |
*Note: US dimensions (inches) are nominal. Please refer to metric dimensions (mm) for exact engineering specifications. Flow rates are estimates; consult our engineers for system design verification.
- Residential Water Softeners
- Residential Well Water Treatment
- Light Commercial Water Softeners
- Point-of-Entry (POE) Filtration Systems
- Activated Carbon Filters
- Media Filters (e.g., Birm, Greensand)
- Sediment Filtration
- Small RO System Pre-treatment
