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400-1990

Pump Union 400-1990

Part #: 400-1990

$4.12
In stock — ships today
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1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this union/fitting

The Waterway Pump Union 400-1990 is an essential plumbing component that connects your spa pump to the system's piping. This OEM replacement part features 1" FBT (Female Buttress Thread) x 1" slip connections, making it compatible with most standard Waterway pump installations in residential spas and hot tubs.

Engineered to Waterway's exact specifications, this pump union ensures a secure, leak-free connection that maintains proper water flow and system pressure. At Bubbles Supply, we guarantee this is the exact fit for your original part, backed by our 1-year warranty and same-day shipping on orders placed before cutoff. The durable construction withstands spa chemicals and temperature fluctuations for reliable long-term performance. Always verify your existing union's thread type and measurements before installation to ensure proper fitment with your spa's plumbing configuration.

Exact part number

400-1990

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Also known as / Replaces

This part replaces or is interchangeable with:

  • 1-inch pump union
  • pipe union
  • plumbing union
  • pump union
  • spa pump union

Looking for an older part number? Check our supersession lookup tool

Technical specifications

Union size
1 inch

Plumbing notes

  • Union size: 1 inch

Need help measuring? Email hello@bubblessupply.com with a photo of your existing plumbing.

Common symptoms this part fixes

If your spa is showing any of these signs, this part is likely your fix:

  • Active water leak at pump inlet or outlet connection
  • Union cracked or broken from overtightening or freeze damage
  • Stripped or cross-threaded union threads causing drip
  • Union body warped or discolored from heat exposure
  • Leaking union causing loss of prime at pump

Not sure if this is your problem? Try our diagnostic centre or .

Before you buy — quick checklist

  • Confirm your existing union is 1" FBT x 1" slip — measure before ordering
  • Inspect whether the leak is at the union body itself or at the o-ring seat
  • Check both the pump-side and pipe-side connections for thread type compatibility
  • Verify this is the pump union and not a heater or manifold union — location matters
  • Note whether your spa has two unions per pump (inlet and outlet) — you may need a pair

Reading the checklist now prevents 90% of returns. Worth the 60 seconds.

Install difficulty: Medium — Some experience neededTypically 30–60 minutes

What's in the box

  • Pump union body
  • Union nut
  • O-ring

If your order is missing any items listed above, contact hello@bubblessupply.com within 48 hours of delivery.

Warranty

1 year manufacturer warranty against defects

Covers manufacturing defects. Does not cover improper installation, normal wear, or accidental damage.

Warranty claims: warranty@bubblessupply.com

Perfect Fit Guarantee

Ordered with our help and the part doesn't fit? Contact us before installation. We'll resolve it with an exchange, replacement recommendation, or return approval.

Learn about our Perfect Fit Guarantee →

Shipping

We ship across the US and Canada. US orders ship from our US warehouse to US customers; Canadian orders ship from our Canadian warehouse to Canadian customers — no cross-border shipping, no surprise duties. In-stock orders placed before 3pm CT ship same day. Standard shipping $9.95 flat rate. Free shipping on orders over $200. Express options available at checkout.

Returns

30-day hassle-free returns on unused parts in original packaging. Contact us before returning to receive your RMA number.

Frequently asked questions

Check the Compatibility section above to confirm fitment for your spa brand and model. If your model is not listed, use our fitment selector at /pages/find-my-part or ask our parts AI for a personalized recommendation.

In-stock orders placed before 3pm CT ship the same day. You will receive tracking information by email as soon as your order ships.

We accept returns within 30 days of delivery for unused items in original packaging. Email returns@bubblessupply.com with your order number to start a return. Installed electrical parts cannot be returned for safety reasons.

Yes, all new parts come with a 1-year warranty against manufacturing defects. Warranty does not cover damage from improper installation or normal wear and tear.

Customer reviews

AI Fitment Assistant

Tell us your spa model and we will confirm this part fits before you buy.

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