Freestanding bath p trap

[NotSureHow]

I want to replace my old cast iron roll top bath with a new roll top bath — either cast iron or acrylic.

I have been looking at the current plumbing to see what new bath I could have so that I didn’t set my heart on a specific bath only to find out that it wouldn’t be suitable, and noticed that the p trap is not very deep - about 25mm depth of seal. (I believe that the pipe eventually discharges into the soil stack as the house has no gullies but there is no problem with any smells). The underside of the bath is about 140mm above the floor and the opening in the bath for the drainage connections is 115mm above the floor. I have attached a photo - please ignore the dust!!!

When looking at new baths, I have seen that they are not much higher off of the ground than my current one. They also look to have p traps fitted that are not very deep.

I have looked at current building regs and I believe 50mm depth of seal or equivalent is required so I don’t quite understand why there are so many baths that are so low and so many bath p traps that don’t meet the regulation 50mm.

Am I measuring the depth of seal correctly - from the top of the dip of the trap to the bottom of the outlet? Could someone please explain to me where I am going wrong here? I realise it’s probably something really obvious but I have a very limited knowledge of plumbing.

Thanks.

 

[jj4091]

Not a plumber but I would say no you are not measuring correctly. It should be from bottom of outlet to bottom of bend. I don't think products that didn't meet building regs. would be sold.

 

[RrogerD]

Not a plumber but I would say no you are not measuring correctly. It should be from bottom of outlet to bottom of bend. I don't think products that didn't meet building regs. would be sold.

Not necessarily. See attached quote from Toolstation.com site

 

[jj4091]

Op is talking about a bath waste not a shower one. I admit I don't know anything about regs but I stilll think he is measuring wrongly

 

[NotSureHow]

Thank you both for taking time to give me your feedback. You measure the depth of seal the same way for either a bath or shower trap. For example, here is a trap that states it is suitable for either a bath or shower and says it has a 19mm trap depth. If you look at the drawing it shows the 19mm is from the top of the dip of the trap to the bottom of the outlet.

https://www.diy.com/departments/plu...-and-waste-pipe-solution/5055967917538_BQ.prd