I can see that you're an expert in GRP, but how many portable toilets have you emptied?  I do this for work and know what I see.  And smell.   Just because nobody has documented it doesn't mean it's not a thing.  I wouldn't use GRP. You would. It's all good. 

Hi Pete . I can only add that I have been involved in the GRP Industry for over 30 years and have never come across any reference to odour retention in GRP.
As an aside the OP is talking about Portable Toilets not Portable Toilet Cabins.
Cheers   Ross

Hi Ross,

Don't get me wrong.  Fibreglass as a construction medium has some great uses.   I've paddled enough fibreglass kayaks and sailed enough GRP dinghies to know that.  But the question was about using fibreglass for portable toilet cabins.  Years of hands-on portable sanitation experience has taught me that fibreglass isn't a good choice for toilet cabins.  Even less so for holding tanks.  I don't know the science, but I do know that fibreglass cabins soak up the smell and you can never get rid of it.  Would I walk away if I had to choose between a fibreglass portable toilet and no portable toilet? Absolutely not. Would I buy portable toilets for a commercial fleet? Never.

It's a good debate though and I appreciate the wider issues.  I'd be happy to devote an episode of the podcast to the debate if you'd like to take part. I'm sure the listeners would enjoy it.

Pete

Pete I have to differ with you on Fibreglass (GRP) as a construction medium. GRP is not porous as any boating showroom will attest. The use of moulded plastic is a different matter as some compounds will perform badly in sunlight. 
GRP is probably the best medium around for small run special uses as it is a low cost and exacting manufacturing method.
Ross

If you are considering using it for the shelter of the toilet, they are HOT. I have seen many of these in a village in Mexico. They are convienet as far as their ability to be customize and prefabricated, but as a shelter, i do not recommend them.

for the toilet itself, i have no comments

-- *David A. Bates*

Hi Sylvia,

Fibreglass isn't a great choice for cabins.  It's porous and will absorb contamination. Ok, you will clean it, but in my experience, you will never get rid of foul smells.  The walls and roof of your cabins will need to be quite thin and because they will be exposed to UV, it will be susceptible to damage.  Even with a UV inhibitor, it will go brittle, split and crack.   I know you are worried about cost, but you might find a better solution by importing. 

Pete

Update:
I have found assistance. 

Thank you. 

Greetings,

I work for a sanitation startup and my teammates and I are developing a portable toilet that works the same as a porta porti. We want it to be locally made in Kenya using fiberglass as importing  is expensive. We are looking for an expert who can work with us voluntarily to advise us on how to get precise designs as that in turn affects the functionality of the toilet. We have 2 prototypes so far made from steel and both have leakage challenges due to lack of design and manufacturing precision.  Any assistance provided will be highly appreciated. My email is This email address is being protected from spambots. You need JavaScript enabled to view it.


Cheers.
Sylvia