Building an enclosure for the treatment plant air pump - ideas and tips?

[Tom]

Hi all. I've got to get round to building a soundproof enclosure for our treatment plant air pump as I'm fed up with the faint drone when I'm sat outside.

We've got a Conder, so the air pump currently sits under the main lid of the unit. I'm thinking I need to build a structure with some mass to prevent transmission of sound, so was thinking I'd pour a small slab, say 50cm2, then build a tiny enclosure with concrete blocks. I guess I'd include a short length of ducting up through the slab for the power and air hose. Is this the right way to go? I'm not sure what I'd use for a "door" on the front, or what to use as a roof - I have some (block and) beam offcuts so could use these to make a flat solid concrete roof perhaps, with some corrugated tin over the top.

Has anyone built their own enclosure, have any tips for what works well or even some pictures? 

Thanks all!

[ProDave]

Before you get too carried away, I quietened our Conder simply by placing a standard 100mm concrete block in the chamber so the pump sits on that now, not the plastic that it used to sit on.

 

Still not silent but a LOT quieter.

[JohnMo]

Ours is a separate box really noisy so buried the bottom part in soil - way less noise - most the noise is vibration induced.

[Gone West]

Our box was remote and designed to be half buried in soil. It was quiet if more than a metre away.

[Nickfromwales]

23 hours ago, Tom said:

with some corrugated tin over the top

Don't use this, as it will be thin enough to be a resonator / acoustic radiator. Concrete paving slab would be weathertight and have some weight to it to help out here.

[saveasteading]

It's poor if they haven't designed the pump to be quiet. It is probably cobbled in to the already designed tank as an afterthought, with plastic and screws.

I agree with the earth and concrete slab principle if that works.

[Alan Ambrose]

I'm wondering whether modulating the speed down, if that's possible, will make it quieter?

[Nickfromwales]

26 minutes ago, Alan Ambrose said:

I'm wondering whether modulating the speed down, if that's possible, will make it quieter?

That would be in 'violation' of the MI's?

 

Deal with the noise pragmatically, and don't compromise the functionality of the STP!!!

 

If folk are reading this, ahead of an intended install, then they will be forewarned / forearmed sufficiently to avoid the issue with more robust methodology.

[Roger440]

7 hours ago, saveasteading said:

It's poor if they haven't designed the pump to be quiet. It is probably cobbled in to the already designed tank as an afterthought, with plastic and screws.

I agree with the earth and concrete slab principle if that works.

Im not sure any of them are "quiet".

 

The vortex i had was hopeless in that regard.

 

Much work was carried out to make it quiet. Whilst 90% better, i was never happy with it. If id stayed, i would have moved it some distance away into a summerhouse we had there. Would have needed a bigger compressor due to distance though.

[saveasteading]

5 minutes ago, Roger440 said:

Im not sure any of them are "quiet".

Can't hear the Marsh Ensign pump. Well I can't anyway.

[Roger440]

As Nick said, mass is what you need. No tine, just concrete.

 

Then line the inside with that egg crate noise absoroption foam.

 

And most important rubber mounts. If i was doing it again, it would be double insulated, ie compressor rubber mounted to a frame using proper rubber mounts, like a car gearbox mount or similar,  wood frame  if you can, which is in turn, rubber mounted to the concrete slab base.

 

Keep an eye on the air delivery hose, this was resting on the base of the plastic duct, which then transmitted resonance to the tank.

 

Sadly it appears beyond the wit of man to design a "silent" sewage treatment plant. Once again, the building industry is miles behind. I guess if you live in a releatively noisy environment it bearable, but when its really quiet on a nice evening all you can here is the bloody pump running!

[Roger440]

Just now, saveasteading said:

Can't hear the Marsh Ensign pump. Well I can't anyway.

Well thats good news, but as above, really depends on background noise. Mind you, the average ASHP will drown it out.

[SteamyTea]

Is there any way, without violating the warrantee, to baffle the intake.

Induction can be one of the noisiest parts of a pump.

[saveasteading]

1 hour ago, Roger440 said:

really depends on background noise

If I can't hear it above the breeze in the trees, or the birds singing, then that isn't sound let alone noise.

 

38 minutes ago, SteamyTea said:

to baffle the intake.

Do we have any sketch or description?

It's just a small box with air hoses in and out, and a cable, isn't it? So maybe just a lump of foam between it and an adjacent surface?

[SteamyTea]

2 hours ago, saveasteading said:

maybe just a lump of foam between it and an adjacent surface

Bit more sophisticated than that.

While this is for variable speed and multi cylinder ICE induction systems, the theory is the same.

 

https://www.researchgate.net/publication/326440306_A_STUDY_ON_THE_DESIGNS_OF_THE_RESONATOR_FOR_REDUCING_RESONANCE_NOISE_OF_INTAKE_SYSTEM_IN_VEHICLE

[dpmiller]

Solido Smart- compressor, sitting on a foam pad, is in a sealed "bucket" which sits atop the airlift tube. This is in free air under the double-skinned plastic manhole cover. Intake pipe is 30ft away in the hedgeline.

 

Zero noise from the inlet, you can't hear the compressor from more than about 10ft from the manhole. Only real noise is splashing water when it's doing it's twice-daily pumpout

[FarmerN]

Changed the plastic box my compressor was mounted in because of vibration noise, but now there is a little gap and a mouse has taken up residence. Chewed cable or pipe next I guess!

Nothing is ever simple!

The pump is quite , if you take cover off and press down on it , it’s all vibration noise.

[JohnMo]

16 hours ago, saveasteading said:

Can't hear the Marsh Ensign pump. Well I can't anyway.

Is with without hearing aids😀

[Tom]

On 22/08/2026 at 12:36, ProDave said:

Before you get too carried away, I quietened our Conder simply by placing a standard 100mm concrete block in the chamber so the pump sits on that now, not the plastic that it used to sit on.

 

Still not silent but a LOT quieter.

 

Good idea, just tried it with mine and not enough "head room" to sit the blower on a block unfortunately (guess your STP uses an additional riser).

 

I think a remote, block-build little enclosure is the way to go, just need to sort the design.

On 23/08/2026 at 09:45, Nickfromwales said:

Don't use this, as it will be thin enough to be a resonator / acoustic radiator. Concrete paving slab would be weathertight and have some weight to it to help out here.

 

Good idea to use a paving slab as a roof.

 

The thing I need to resolve in my mind is what to make for a door. Twin OSB skin with some acoustic isolation material in the middle? How/where to place an air intake? I guess some sort of baffled penetration that goes through the door? I'll try and draw what I'm thinking...

[saveasteading]

32 minutes ago, Tom said:

Twin OSB skin with some acoustic isolation material in the middle?

OSB will fall apart with dampness.  I'd suggest using brick or block, and it can probably be really rustic, simply stacked and with no footing, then the slab on top. The inside could be stuffed with the kind of rockwool that is water resistant, or use foam ( the  non absorbent kind, salvaged from last year's collapsed garden chair.) Rr bubble wrap.

[Tom]

Not sure I follow you - are you sating just stack some blocks up on earth? Here's a picture of what's in my mind at the moment. Block walls on small poured slab, paving slab roof with slope front-back. Then I would need to close the opening at the front.

[saveasteading]

1 hour ago, Tom said:

are you sating just stack some blocks up on earth? 

Yes. Dig out the topsoil. Add a footing if you want but sand would suffice. But you should need to maintain this so seldom that you just lift off the slab roof and a block if necessary. No need for an open side.