Osma UltraRib
Most frequently asked questions

Osma Below Ground Drainage

Our technical design team are on hand to help with any questions about our full product range including the Osma Below Ground Drainage. We caught up with the team to find out the answers to some of the most commonly asked technical questions.

1. What is the maximum jetting pressure for plastic drainage?

The maximum bar pressure for jetting plastic pipework is 2600 bar, as per the jetting code of practice.

Osma UltraRib


2. What is the maximum temperature your products will take?

Pipes and fittings manufactured from PVC-U or ABS

- Osma soil systems and ABS solvent weld waste system – OsmaWeld: suitable for use with intermittent discharges or water up to 90 degrees. 

Pipes and fittings manufactured from PVC-C or Polypropelyne.

- PVC-C Solvent waste system, PP Push-fit waste systems (to BS EN 1451 and BS EN 1566-1) and V-joint Traps: suitable for use with intermittent discharges of water upt to 100 degrees c.

PVC-U and ABS overflow pipes and fittings

- Solvent weld overflow system: Must not be used where hot water discharges are likely to occur.

3. What are the minimum depths pipework can be laid at under the road?

If the road is in an adoptable situation, the minimum depth, to the crown of the pipe, is 1200mm. However, if the road is a non-adoptable situation, then the minimum depth of the crown of the pipe is 900mm.

4. What are the minimum falls that Osmadrain and Osma UltraRib can be laid to?

4"/110mm OsmaDrain - 1:80 (Minimum of 1 WC)
6"/160mm OsmaDrain - 1:150 (Minimum of 5 WC’s)
6"/150mm UltraRib - 1:150 (Minimum of 5 WC’s)
9"/225mm UltraRib - 1:200
12"/300mm UltraRib - 1:300


5. What size bedding and side fill do I need to lay my pipework?

Materials that are used for bedding should contain no particles with sizes above:
22mm for pipe sizes <= 200mm
40 mm for pipes > 200 u to <+ 600mm


6. Do you have health and safety sheets for your products?

Yes, these can all be found and downloaded via the Wavin website.

Find out more about our Technical Advisory Service