Waterco Half Barrel Unions - 50mm

Waterco Half Barrel Union - 50mm

Genuine Waterco 50mm half barrel union, comprising the threaded locking nut, the glue-in tail piece and the union O-ring. Waterco part number 634024B (also listed as 1533537, 634024BLK). This is the standard 50mm union used across most of the Waterco pump range, plus Waterco filters, multiport valves and the Aquaswim, Baker-Hydro, Lacron Grange and Maxi Grange badged equivalents.

• Physically Stocked, unlike most "drop-shipping" websites.
• Shipped from VIC, NSW, WA, QLD

What's Included

• 1 x threaded barrel union locking nut
• 1 x glue-in tail piece (solvent weld to 50mm PVC pressure pipe)
• 1 x union O-ring

Quick Size Check

This is the 50mm union. The glue socket accepts 50mm PVC pressure pipe, which has an actual outside diameter of around 60mm — not 50mm. If the pipe going into your existing union measures roughly 60mm across the outside, this is the correct size. If it measures around 48mm OD you have 40mm pipe and need the 40mm union instead. Measure the pipe, not the union nut.

Compatible Waterco Pumps

Supastream range

• Supastream 50, 75, 100, 125, 150 — 50mm port models (WFE1)
• Aquaswim Series 40S — same pump, Aquaswim badging
• Lacron Grange — same pump, Lacron badging

Supatuf range

• Supatuf 75, 100, 125, 150, 200, 250, 300
• Supatuf Eco 100
• Aquaswim Series 50 — same pump, Aquaswim badging

Hydrotuf range

• Hydrotuf 100, 125, 150, 200

Hydrostorm range

• Hydrostorm 75, 100, 125, 150, 200, 250, 300, 350
• Hydrostorm Eco 100
• Hydrostorm Eco-V 100
• Hydrostorm Eco-V 150
• Hydrostorm Plus 100, 125, 150, 200, 250
• Aquaswim Series 50T — same pump, Aquaswim badging
• Maxi Grange — same pump, Lacron badging

Turboflo range

• Turboflo 100, 125, 150, 200, 250, 300, 400

Baker-Hydro badged pumps

• Waterco pumps sold under the Baker-Hydro brand share the same 50mm pump body and union. If your Baker-Hydro pump has a 50mm threaded port with a barrel union, this is the correct part.

Compatible Waterco Filters, Valves & Equipment

• 50mm multiport valves — Waterco top mount 228053 and 228058, side mount 2290512
• Micron side mount sand filters — 50mm port models
• Micron side mount commercial filters
• SMD / SMDD side mount deep bed filters
• Thermoplastic and Hydron filters using the 50mm common parts group
• Fulflo Tri Cartridge filters — TC300, TC400, TC500
• Fulflo / Astra D.E. filters — P2027, P2031, P2036, P2048
• Leaf Trapper

Will NOT Fit — Check Your Port Size First

Waterco uses a different union at every port size, and they are not interchangeable. If yours is not 50mm, you need one of these instead:

• 40mm — part 122243B. Click here for the Waterco 40mm half barrel union.
• 50mm x 40mm reducing — parts 122257BLK / 634024542, used where a 50mm port is plumbed down to 40mm pipe
• 65mm x 50mm — part 63406550BLK, used on Hydrostar 200–350, Hydrostorm Plus 300–400 and Supaflo
• 80mm — part 6340803, used on Hydrosteel and Hydrostar Commercial
• 100mm — part 6340801, used on large commercial filters and Hydron

Also not this part: Opal and Opal XL cartridge filters use their own union set (AXFI014 tail, AXFI016 lock ring, AXFI018 O-ring). Large Baker-Hydro commercial strainer housings use 4" and 6" flanged connections rather than a barrel union. Portapac and Aquastream Solar use the 50/40mm S13185A union.

Part Numbers & Search References

• 634024B (current Waterco part number)
• 634024BLK
• 1533537
• WC634024BLK (Waterco USA reference)
• Union O-ring only: 6340241 — BS332 / P2027-48
• Locking nut only: 6340242B

Common search terms: Waterco 50mm half union, Waterco barrel union 50mm, Waterco pump union kit, Hydrostorm union, Supatuf union, Hydrotuf union, Turboflo union, Lacron Grange union, Baker-Hydro pump union, Aquaswim union, 634024B, Waterco 2 inch half union with o-ring, Waterco pump tail piece and nut.

Understanding 50mm Nominal Sizing

In plumbing, named sizes are not measured sizes. A pipe called "50mm" or "2 inch" does not measure 50mm across — it follows nominal sizing, an internationally standardised naming convention. 50mm PVC pressure pipe has an outside diameter of approximately 60mm. Always use the OD of the pipe to confirm the fitting size.

Fitting Notes

• Solvent weld the tail piece to 50mm PVC pressure pipe using an approved priming fluid and PVC cement. Allow full cure before pressurising.
• Seat the O-ring in the tail groove and lubricate with a silicone-based lubricant only. Petroleum jelly and mineral greases swell and destroy the rubber.
• Hand tighten the nut only. These unions seal on the O-ring face, not on thread compression. Multi-grips and pipe wrenches crack the nut and do not improve the seal.
• If a union weeps after tightening, the cause is almost always a nicked, flattened or dirty O-ring, or grit on the sealing face — not insufficient torque.
• Support the pump and pipework so the unions are not carrying pipe weight or misalignment. Side load is the most common cause of a cracked union nut.

Why Replace A Barrel Union?

• Cracked or split locking nut, usually from over-tightening or UV embrittlement
• Persistent weeping at the pump inlet or outlet
• Air being drawn in on the suction side, causing loss of prime or a pump that will not hold water
• Stripped or cross-threaded nut that will no longer pull up square
• Damaged tail piece sealing face
• Retrofitting a new pump onto existing pipework

A weeping union on the suction side is worth attending to promptly. It draws air rather than leaking water, so there is no puddle to warn you, and running a pump with entrained air will damage the mechanical seal.

Frequently Asked Questions

How many do I need?
Two for a complete pump changeover — one per port. One only if you are replacing a single failed side.

Does it include the O-ring?
Yes. The union O-ring (6340241) is supplied with it. You can also buy that O-ring separately if the nut and tail are still sound.

How do I know I need the 50mm and not the 40mm?
Measure the outside diameter of the pipe entering the union. Around 60mm OD is 50mm pipe and takes this union. Around 48mm OD is 40mm pipe and takes part 122243B.

Will it fit my Baker-Hydro pump?
Yes, if it is one of the Waterco pumps sold under the Baker-Hydro brand with a 50mm barrel union port. The pump bodies are shared, so the union is the same. Large Baker-Hydro commercial strainers are flanged and use a different connection.

Will it fit my non-Waterco pump?
Only if that pump was built on a Waterco body. Aquaswim, Baker-Hydro, Lacron Grange and Maxi Grange are re-badged Waterco pumps and do fit. Other brands use their own thread forms — an Astralpool, Onga, Davey or Poolrite 50mm union is not interchangeable with this one even though the pipe size matches.

My pump is 50mm but the old union looks different.
Waterco revised the union around 2001. Compare the nut thread and the tail length before ordering, and send us a photo if you are unsure.

Can I use thread tape on it?
No. The seal is made by the O-ring against the port face. Tape on the barrel thread does nothing useful and can prevent the nut pulling up square.

Not Sure Which One You Need?

Send us a photo of your pump label and the existing union and we will confirm the correct part and quantity. Waterco has used at least six different union sizes across their range, and the wrong one is a wasted trip.

Manufacturer Catalogues, Diagrams & Part Numbers

Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogue: Waterco Catalogue 2026