Waterco Trimline MkII Cartridge Filter Tank Lid O-Ring - 221mm - 62021
Waterco Trimline MkII Cartridge Filter Tank Lid O-Ring - 221mm - 62021 is temporarily out of stock and will ship as soon as it's available.
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Don't Guess - Ask Us!
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Waterco Trimline MkII Cartridge Filter Tank Lid O-Ring - 221mm - 62021
Waterco Trimline MkII Cartridge Filter Tank Lid O-Ring - 221mm - 62021 is temporarily out of stock and will ship as soon as it's available.
Waterco Trimline MkII Cartridge Filter Tank Lid O-Ring — 221mm
Genuine Waterco tank lid o-ring, part number 62021, sized 221mm to match the MkII lid. This is the seal between the lid and the filter body on the earlier Trimline MkII cartridge filter — the part to replace when water weeps or sprays from around the lid, or when the lid will not hold pressure after servicing.
Specifications
| Part Number | 62021 |
| Manufacturer Description | Lid O-Ring MK2 |
| Size | 221mm — matches the MkII lid outside diameter |
| Brand | Waterco |
| Suits Lid | 62020 — MkII lid, 221mm outside diameter |
| Quantity Per Filter | 1 |
MkII or MkIII? Measure the Lid
This o-ring is for the MkII only. The MkIII uses a different, smaller seal and the two are not interchangeable. The quickest way to tell them apart is the lid diameter:
- MkII lid — 221mm outside diameter — lid o-ring 62021 (this part)
- MkIII lid — 214mm outside diameter — lid o-ring 62026
Some suppliers list a single o-ring as suiting both the MkII and MkIII. Waterco do not — they specify separate part numbers. Measure across your lid before ordering, or send us a photo of the filter and the lid.
Fitting
Shut the pump down and release tank pressure at the air bleed before removing the lid. Clean the groove and the sealing face, then fit the o-ring and give it a light smear of silicone-based o-ring lubricant. Do not use petroleum grease — it swells and degrades the rubber. Seat the o-ring fully before refitting the lid and lock ring, and re-pressurise slowly while checking for leaks.
Related Trimline Parts
- 62020 — MkII lid, supplied with o-ring
- 62026 — MkIII lid o-ring, 214mm
- 62024BLK — Lid lock ring
- 620221 — Air release valve, MkII and MkIII
- 620341 — Union o-ring, 40/50mm MkII
Manufacturer Manuals, Diagrams & Part Numbers
Need exploded views, spare part numbers, diagrams, or more product information? See Waterco's Trimline Cartridge Filter manual.
Important Before Ordering: Please ensure you order correctly. Confirm this product is suitable before ordering. Use the manual above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers, and any labels.
As with all products, these must be diagnosed and fitted by a qualified and experienced person.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems and other plumbing areas so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate.
Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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