Septic tank smells despite just being emptied. Anything we can do?

[MisterBoy]

We have a modern-ish tank, 20-30 years old, which the previous owner had installed. I only noticed recently that it is fairly smelly nearby - using the garden differently so we are near it more than before. Not terrible but noticeable.

I thought it was just full but after it was emptied nothing has changed. The smell is definitely from the tank not the drainage channels, etc. No signs of any damp patches, all looks fine.

Is this just the nature of these things, I guess it might be? I assume it has some sort of vent pipe(s), it's not air-tight. Got me thinking if you can buy any caps or even filters - or maybe these are standard and could wear out?

 

[lostinthelight]

After emptying it takes a while to get working and sweeten up a little.do you have an open soil stack rising above your roof to vent it?
We dont use bleaches or other harsh chemicals that tend to kill the bacteria required to keep the smells down

 

[MisterBoy]

After emptying it takes a while to get working and sweeten up a little.do you have an open soil stack rising above your roof to vent it?
We dont use bleaches or other harsh chemicals that tend to kill the bacteria required to keep the smells down

No stack, it's in our garden at ground level. It's when you're in the garden you notice it which is not ideal now the garden is the only place we can see people

I don't know the model but it appears to be like this, we have two pipes breaking the ground presumably from those black 'T' parts which I presume are either inspection or vents or both. I think they are full of water though I haven't had that close a look yet. Visually, it's screened with bushes.

This is the sort of thing I wondered exists: https://www.amazon.co.uk/Studor-Maxi-Filtra-Vent-Septic-Tank/dp/B00FQEX1ZG

Not entirely sure if you just bung one on each pipe... seems pricey for what it is if I need 2!

 

[lostinthelight]

You should have a pipe visible up the side of your house or a boxed internal one that your foul water discharges into to carry it to the tank ,this pipe should discharge gasses above the roof

 

[MisterBoy]

You should have a pipe visible up the side of your house or a boxed internal one that your foul water discharges into to carry it to the tank ,this pipe should discharge gasses above the roof

We do. But the septic tank is about 50m away and several metres down hill from the house- house and garden are sort of separated. There are no issues with the drains at the house, it is the tank itself which smells.