We got our ensuite renovated in late 2014, prior to that we had no issues with smells. Ever since the Reno, the floor drain has a sandy / muddy smell. It's really hard to explain it, it's not a typical stinky drain / sewage smell. I've tried pouring buckets of really hot water into it followed by disinfectant and bleach but no success, the smell is back within hours. Any ideas on what might be causing it or tips on how I can get rid of it? It is one of these drains if this makes a difference: ImageUploadedByThe Bub Hub1458335460.763447.jpg
Oh also I have checked and there's no hair or anything visible on there, just a bit of dust around the top.