While I love the sound of falling water, I know some people can find it irritating. If that’s you then you probably want to know how to reduce waterfall noise. Here’s a quick answer:
The easiest way to reduce waterfall noise is to put something at the bottom to break the water’s fall. You’d be best to use something soft like a sponge, but you could also fit a ramp so the water pours rather than falls. This will drastically reduce the noise it makes.
In this article, I’ll look at the science behind waterfall noise along with the best ways to reduce it. Hopefully, by the end, you’ll have a good solution for this distraction.
Why Does Falling Water Make Noise?
The most common sources of waterfall noise in the home are either backyard water features or fish tanks.
While many people find the sound relaxing, it can be irritating if you need to concentrate on something important or are trying to sleep.
But why exactly does water make noise when it falls?
The science behind waterfall noise is quite interesting but can become complicated when you start involving fluid mechanics.
At the most basic level, water falling has some amount of kinetic energy from its movement. When this comes into contact with the surface of the still water, the kinetic energy becomes vibrations, which convert into sound waves.
But in more detail, the water droplet pushes the water’s surface down and penetrates into the water to a degree. This process may or may not be strong enough to break the water’s surface tension.
If the water droplet doesn’t have enough energy to break the surface tension, the water closes around the droplet, which traps some air inside the “bubble”. This bubble then pops, releasing the air, which creates a sound.
But if the water’s surface doesn’t completely close around the drop before the drop’s surface collapses, you end up with a kind of teardrop-shaped pocket of air beneath the water’s surface.
Gravity then restores the water’s surface equilibrium, and in the process forces the trapped air out.
Any sound caused during this process by the water vibrating resonates at a frequency that’s inversely proportional to the volume of the air trapped under the surface.
In short, this means that smaller air pockets resonate at a higher pitch than larger ones and that the pitch increases as the air pocket decreases.
The water droplet basically becomes a miniature Helmholtz resonator.
This process is the same regardless of the volume of water that’s falling into a still body of water. But obviously the more this happens simultaneously, the louder it’ll be.
While it’s not strictly necessary to understand this process in order to reduce waterfall noise, it does help in understanding why the solutions below help.
What Kind Of Environment Is Your Waterfall In?
Before working on your waterfall, it’s worth taking a bit of time to understand its environment and how this might help or hinder your solutions.
If your waterfall is part of an outdoor water feature, there’s probably plenty you can do to make it quieter.
But it’s also worth considering if there are any surrounding walls that the noise can bounce off. Echo and reverberation can make the waterfall sound louder than it actually is.
The other thing worth considering, particularly if this is an indoor problem, is whether there are any living creatures involved.
For example, if you’re trying to reduce the noise of falling water from a fish tank pump then you need to be very careful with what you do. Fish are very sensitive to chemicals, and even a bit of plastic might be enough to kill them.
Take some time to think about where your waterfall is and how this might affect what you can actually do.
How To Reduce Waterfall Noise
Now we can move on to some suggestions for making a waterfall quieter. It’s fair to say that you’ll never make a flowing body of water completely silent, but trying some of these methods will make a difference.
I recommend reading through them all before trying one, as some are more suitable for use in aquariums, but all are suitable for trying in outdoor water features.
1. Add something to cushion the water’s fall
My first suggestion is to put something soft in the pool to essentially break the water’s fall.
This will basically prevent the falling water from making contact with the water’s surface, instead falling on to a soft object. Hopefully, this will make less noise.
You can fix the sponge in place using some cable ties, or if the pool base is soft, you can push a nail or skewer through.
The only downside to this option is that a sponge is great for harboring bacteria. This won’t be a massive problem if you’re using it in an outdoor water feature, but might in a fish tank.
To overcome this, simply rinse it out once or twice a week.
Also, if you are using this in a fish tank, clean the sponge thoroughly before first use. The chemicals used to make the sponge will be toxic to fish. Simply steep it in boiling water several times and rinse thoroughly.
2. Use air bubbles to disrupt the water surface tension
As I discussed above, the noise made by falling water mainly comes from it making contact with the surface of the pool.
Therefore, an easy way to reduce this problem is to disrupt the surface tension. Doing this will mean that air pockets can’t get trapped in the water, but will simply bubble out.
A fish tank air pump is perfect for this job. They’re designed to aerate aquarium water so produce fine streams of bubbles. What’s more, they’re pretty quiet too.
Air pumps generally aren’t too powerful because they’re not designed to circulate and filter the water, but put air into it.
Be careful with which model you buy because if you have a large pool then you’ll need a more powerful air pump. The surface tension will be greater on a large pool and you’ll need more power to disrupt it.
3. Run the water down a smooth surface
One way to drastically reduce the amount of noise a waterfall makes is to create laminar flow. Laminar simply means smooth and is when water flows along a surface without turbulence or lateral mixing.
For example, think of how water flows from a tap before it starts breaking up into smaller streams. This is a common example of laminar flow.
Many water features will have the waterfall down a rocky surface, or perhaps one covered in vinyl.
To make this process much quieter, simply replace this uneven surface with a smooth one.
You can basically use any material you want for this job, but something like mass loaded vinyl (Amazon link) might be a good idea.
First, it has a very smooth surface. Also, it’s very flexible, so you can lay it easily on an uneven surface.
MLV is a soundproofing material, so its limp mass properties will come in handy here. This means it won’t vibrate and transmit sound waves, so will reduce sound transfer into and out of the falling water.
Your goal here is to create a smooth, gentle decline for the water to flow down. In short, you want to make it so the water pours rather than falls. You should find this does a good job of reducing the overall noise levels.
4. Build some sound baffles
This option is generally more applicable to outside water features, particularly those with walls around them.
Solid, flat surfaces are great for reflecting sound waves, and if your waterfall is in a courtyard or walled corner, for example, it’ll sound much louder than if it was in an open area.
Noise absorbing panels are really easy to build yourself. Follow this guide:
- Build a frame from lumber that measures 4’ high and 2’ wide.
- Fix a reinforcing bar across the middle for rigidity and to hold your insulation in place.
- Fill the frame with mineral wool insulation (Amazon). These panels shouldn’t be too far off the right size, but cut to fit as necessary.
- Wrap the frame with some waterproof canvas (Amazon) and staple down, pulling it nice and tight.
You can now hang several of these sound baffles around your water feature and should notice some noise reduction.
The waterproof canvas should have a fairly wide weave so that sound waves can enter the baffle and get absorbed by the rockwool insulation.
Some Final Thoughts
Hopefully, this article has given you some help on how to reduce waterfall noise.
While you’re never going to get it completely silent and still have running water, disrupting the water flow or surface tension will do a fairly good job of making things quieter. Just be prepared to get your hands dirty!