Product Description

Waterway 2.5" x 2" Pump Union for Viper Pump with Gasket (400-5990)

Stop your spa leak fast with the exact OEM-spec union your Waterway Viper pump needs. This genuine Waterway replacement pump union delivers a watertight seal at the suction side of your pump — and it ships with a matching gasket included.

Shop and order at Western Tub and Pool
Call us: 1-855-248-0777 | Email: fixmytub@gmail.com

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What Is This Part?

The Waterway 2.5" x 2" Pump Union (Part # 400-5990) is a suction-side pump union fitting designed for Waterway Viper, XP3, and select Executive series hot tub pumps. It connects your spa's 2" suction plumbing to the 2.5" threaded wet end of your pump, forming a secure, leak-free joint.

A matching gasket is included with every unit — so you have everything you need to complete the repair in one purchase.

Product Specifications

How It Works

This union is a two-part fitting — a nut and tailpiece — that allows you to easily connect and disconnect your pump from the spa plumbing without cutting pipe.

• The slip side accepts a 2" PVC pipe or fitting, which is glued in place
• The threaded side screws directly onto the 2.5" threaded wet end (volute) of your pump
• The included gasket seats between the two halves to create a watertight seal
• When you need to service your pump, simply unscrew the union nut — no cutting required

Compatible Pumps and Hot Tub Models

This union is designed for use with hot tubs and spas equipped with the following pumps:

Compatible Pumps

• Waterway Viper series pumps (48 and 56 frame) — 2.5" x 2.5" wet end port
• Aqua-Flo XP3 series pumps (48 and 56 frame) — 2.5" x 2.5" wet end port
• Waterway Executive series pumps — select models (verify before ordering)

Hot Tub Brands That Commonly Use These Pumps

Many hot tub manufacturers source Waterway and Aqua-Flo pumps as original equipment, including but not limited to:

• Strong Spas
• Artesian Spas
• PDC Spas
• Cal Spas
• Dynasty Spas
• Sundance Spas (select models)
• Jacuzzi (select older models)
• Marquis Spas (select models)
• American Whirlpool
• Dimension One Spas (select models)

Not sure if this is the right part for your spa? The pump and plumbing configuration can vary between models and production years. We strongly recommend verifying your part number, pump model, or wet end port size before ordering. See our FAQ section below for guidance.

Why Order from Western Tub and Pool?

Hard-to-Find Parts, Found

We specialize in locating and supplying replacement parts that are difficult to source elsewhere. If you've been searching without success, chances are we have it — or we can help you find it.

Expert Guidance

Not confident you have the right part? Our team has decades of experience diagnosing spa and hot tub issues. Call or email us and we'll walk you through it.

Free Home Tutorials

New to hot tub maintenance? Western Tub and Pool offers free in-home tutorials to help you understand your spa, your water care, and your repair options — because a well-maintained hot tub is a safe and enjoyable one.

Trusted Local Service

We're a real business with real people. When you contact us, you speak to someone who knows hot tubs inside and out.

Frequently Asked Questions

How do I know if this is the correct pump union for my hot tub?

The best way to confirm compatibility is to check the existing union on your pump. Measure the outside diameter of your pump's wet end threads — if it measures approximately 3 5/8" across, this union is likely the correct fit. You can also check the stamped part number on your existing union, or call us at 1-855-248-0777 and we'll help you confirm.

Can I send you photos of my part to confirm the fit?

Absolutely. Email clear photos of your existing union, along with your hot tub's make, model, and serial number, to fixmytub@gmail.com. Our team will review your images and confirm whether this part is the right match before you order.

Is the gasket included, or do I need to order it separately?

The gasket is included with this union. You will not need to purchase it separately.

Do I need special tools to replace a pump union?

In most cases, no. Pump unions are designed for hand-tightening and removal. You may need basic plumbing supplies such as PVC primer and cement if you are also replacing the tailpiece or re-gluing the slip side into new pipe.

What if I can't find my part number?

That's what we're here for. Send us an email to fixmytub@gmail.com with your hot tub's make, model, and serial number, along with photos of the part you need. We'll identify the correct replacement and get back to you promptly.

Do you carry other Waterway pump parts?

Yes. We carry a wide range of Waterway pump components, including wet ends, impellers, O-rings, seals, and more. Browse our online catalogue or give us a call to check availability.

Can't Find the Right Part? We Can Help.

Tracking down the right hot tub replacement part can be frustrating — especially for older or discontinued models. At Western Tub and Pool, helping customers find hard-to-locate parts is one of our specialties.

Here's how to get the fastest answer:

• Have your hot tub's make, model, and serial number ready
• Check your existing part for a stamped part number
• Take a few clear photos of the part and the surrounding plumbing area
• Send everything to fixmytub@gmail.com or call 1-855-248-0777

We'll do the research and get back to you quickly.

Shop and Order at Western Tub and Pool

Whether you know exactly what you need or you're still trying to figure it out, the team at Western Tub and Pool is ready to help you get your hot tub back up and running.

Call us: 1-855-248-0777
Email us:fixmytub@gmail.com

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