20 month old pooping in the bath

[Horehound]

My boy has always only pooped once or twice a week and I'd say 90% of those in the last few months are always in the bath.
I don't think he is constipated because his poops are soft. Occasionally he will poop into his nappy but not often. He goes to nursery 4 days a week and he started there in August. I'd say he has had only 4 dirty nappies there in that time. He seems to wait to be home and with me before he thinks about pooping.
Over the week I see his tummy get bigger and bigger and then he does a huge poop in the bath. I know the warm water will relax his muscles but how do I love away from this routine?
I have bought a potty and talk to him about poops in the potty but tbh I think he's just a touch took young to understand it. I asked him to sit on it before the bath tonight and he didn't want to/kept getting up. Put him in the bath and 5mins in there was a big poop.
I've started giving him Weetabix and cosy milk before bed and I have seen an increase in pooping in the last two weeks but it's still in the bath.
Bit of a pest if he does it not long into bathtime And have to get him out, drain, clean and refill.

Anyone got any tips?!

My younger sister did this every time she had a bath. How do I know? Because we always shared a bath and I remember screaming like a loon for my mum to lift me out immediately!

My DD did this and was constipated. I gave her diluted prune juice regularly and sometimes had to use medication

Excuse the pun but this phases passes

@fairydustandpixies

My younger sister did this every time she had a bath. How do I know? Because we always shared a bath and I remember screaming like a loon for my mum to lift me out immediately!

Lol oh god I can just imagine it! Well we do have another on the way but hopefully it's resolved by the time they'd be sharing a bath together!

@merrygoround88 we do give him prunes to eat occasionally. The thing I wondered about was water intake at nursery. We make sure he drinks with us but I just don't know if they do so that'll be another conversation too.
He eats tonnes of fruit, we call him a little fruit bat!

I should add that one time our shower drain got blocked, we used to put the baby bath in the shower and try and fish the poop out but on 2 occasions the bath tipped over and the offending items headed for the drain.

The plumber who fixed the blockage looked at us like we were animals despite us trying to explain the issue

@Horehound I found the juice better but he may well need the medication.

So many children find it difficult to go during the toddler years

I was going to say it might be constipation, I was thrown when DS went through the same as I always assumed the actual poo when it did come out would look different to how it did.