Clearing muddy water

Clearing muddy dam water (5 steps)


Why does dam water get muddy?

Muddy water in dams, ponds and lakes is often the result of soil particles entering the water which have a similar charge of electrons to one another. This causes the particles to form loose bonds, clumping together and remaining suspended. Whether these particles will settle on their own or not depends on several factors, including the muddiness of the surrounding watershed, the soil type, the water depth, the level of wind and wave action etc.

If the suspended soil particles don’t settle to the bottom of your dam themselves, you may be able to help them through a process of coagulation and flocculation (“floccing”).

What is floccing?

Floccing involves using a product like WaterTreats Clearwater Flocculant at a ratio of approx. 1-5mL per 100L of dam water. The flocculant solution has an opposing charge to the water and suspended material so it attracts the soil particles together and binds them. The clumping particles eventually get so heavy they sink to the bottom, thus clearing your water.

Step 1: Is your water muddy, cloudy or stained?

Before you consider floccing, let’s first make sure your water is actually muddy, not cloudy or stained. What’s the difference? Let’s rule out stained water first.

Stained water

Stained water looks like weak tea. The water is often crystal clear but discoloured by the tannins that come from leaf debris. You can learn more about tannins in dams here but the short answer is unfortunately there is nothing you can do to reduce the colour unless you remove the surrounding trees shedding leaves (something not advisable as this can disrupt the ecosystem in a big way). Instead, it’s best you recognise tannins aren’t a bad thing and get used to the colour.

Muddy vs cloudy water

Muddy water and cloudy water are a little more difficult to distinguish. The key difference is muddy water is compromised of mostly inorganic matter (i.e. soil, dirt) and cloudy water is compromised of mostly organic matter (e.g. micro-organisms, vegetative debris, animal excrement).

Typically you can spot muddy water a mile away. You can’t see into it at all—it looks like a sheet of brown or greyish brown. Although you may see fine particles up close, the colour and texture of the water should appear the same everywhere. When you do look closely you shouldn’t see particles clumped together in areas. Instead, you’ll seen a homogenous substrate of fine sand/soil.

Cloudy water isn’t the same colour or tone throughout. The water is generally clear but you can see some particles in it. Some areas are likely to appear cloudier than others, and if you look closely you can often see organic material (e.g. micro-organisms, leaves, algae, excrement) rather than fine dirt particles. Some areas might also have a green, blue or olive tinge (this is the organic matter).


Which are you: muddy, cloudy or stained?

If your water is stained, unfortunately as mentioned above, there is nothing you can do to permanently remove the colouration. You may be able to remove the colour temporarily using a treatment but the stain will more than likely return. Best you get used to the colour and move on.

If your water is cloudy, we recommend you use a probiotic biological treatment (e.g. Biostim). A biological treatment can help clear your water by getting rid of the organic muck and breaking down the sludge on the floor of your dam. Add a little treatment each month (tablets, powder or liquid) and your water should clear up in no time.

If your water is muddy, go to step 2.

Not sure? We provide free, no-obligation advice. Fill in our Dam Diagnostics Survey and we can help.

Step 2: Collect a water sample

So you definitely have muddy water. Next we need to see just how suspended/buoyant the muddy material is.

You’ll need 1 x bucket (10L or larger) and 5 x 1L clear jars/containers.

Fill the bucket with around 10L of dam water. Use the 1L containers to collect water from various parts of your dam. Mix all the water together.

Next use the jars to take 1L samples from this mixed dam water. So you should have 5 x jars/containers with 1L of dam water in each. Take a photo of the samples and leave them sitting still for one week.

After one week, check the clarity of the water. Is it just as muddy or clearer?

If the water is clearer, it’s likely you have a soil erosion problem or your dam is too shallow causing mud to be stirred up from the bottom. Unfortunately, a flocculant can’t help with this unless you first fix the cause of the issue. This means you’ll need to first figure out what is causing so much soil to enter your water and fix this instead. Get in touch with us and we can help.

If your water samples are still just as muddy after one week, floccing might be an option for you.

Step 3: Diagnose the cause of the muddiness

Even if you completed Step 2 and saw no change in the turbidity of the water, it’s important to run through the list below to make sure none of the listed items apply to you. Otherwise, you might clear your water only for it to immediately muddy again.

Do any of these apply to your dam?

  • Is your dam less than 1m deep? It may be so shallow that mud is being stirred up from the bottom. If this is the case, you may need to consider deepening your dam. Talk to us first, we’re happy to provide free advice.
  • Do you have a yabby problem? A common culprit to dam floor erosion is an overpopulation of yabbies which burrow into the ground. Having a few yabby holes in the floor of your dam is fine, but too many can be a big problem for the health of your dam and the clarity of your water. If this is a problem for you, we recommend setting some traps and getting the population down.
  • Are your dam’s banks without vegetation? If this is the case, we recommend you plant some non-invasive plant species or lay a bed of large rocks which can take the brunt of the wind and wave action, limiting the soil movement. Otherwise, your soil will forever be washed into the water, making it murky.
  • Do livestock have access to the water? Livestock erode the banks and floors of dams and defecate in the water. The best option here is to fence the dam off from your animals and instead give them access to a water trough.
  • Do you have carp or koi (a type of carp) in the water? Both these guys cause muddy water because of the way they feed, sifting the mud through their gills to collect food. Our advice is to never introduce carp or koi to a dam, and if you’ve already introduced such species, try your best to get them out. Otherwise, your water is likely to always be a little murky.

Step 4: Calculate how much flocculant you need

If you’re still reading, we’re assuming you’ve done the above steps and your water is still muddy. This means a flocculant might be right for you. Before you go on to calculate how much flocculant you need though, it’s important to understand that floccing doesn’t always work. Unlike our other treatments (e.g. aeration and biological treatments) which we 100% back results on floccing can be hit and miss depending on many factors. If you want some free advice prior to doing the floccing process, complete our Dam Diagnostics Survey and we’ll be in touch.

To calculate how much flocculant is required to clear your dam water you’ll need a 1L sample of WaterTreats Clearwater Flocculant. This is our flocculant recommendation (it’s our brand), but other flocculants can also work.

It’s important to take your time on this step because with too little or too much flocculant you can have a poor outcome, i.e. you could test 2mL and 3mL per 100L and neither work, but 2.5mL does. The other reason to take your time with your measurements is an extra 0.5mL per 100L over a 1,000,000L dam is a big difference in cost.

Start by diluting 15mL of the WaterTreats flocculant in 985mL of fresh water. This is a ratio of 1:67 (1 part flocculant to 67 parts water).

Now, take a dropper and add 1mL of the diluted WaterTreats Flocculant to the first 1L sample, 2mL of flocculant to the second sample, 3mL to the third, 4mL to the fourth, and 5mL to the fifth.

Leave the samples to settle for a few hours, although you’ll often start seeing results after just a few minutes. What you’re looking for are particles “floccing” (clumping) together. At first, they’ll appear like small pinheads. Then they’ll take on a fluffy appearance as the particles “floc”. When the floc gets large enough, the particles should sink to the bottom.

After a few hours, find the two jars that are the clearest. Redo the testing with another three fresh samples of dam water. This time however, you’ll test new measurements between the two clearest samples. For instance, if the jars with 2mL and 3mL performed best, then you should test three new jars at 2.25mL, 2.5mL and 2.75mL of flocculant. Again, wait a few hours

Now compare all five jars, e.g., in the example above, compare 2mL, 2.25mL, 2.5mL, 2.75mL and 3mL.

Which ratio of flocculant performed best? This will be your ratio per 67L of dam water. This means to calculate the total amount of flocculant you need, work out your dam’s total water volume (length x width x depth) and divide it by 67.

Pro tip when ordering

When you buy flocculant we recommend ordering 20% more than you calculated above. This is because dam water in a dam often acts differently to dam water in a container. The fact is you only get one shot at getting “floccing” right. If you add a certain amount of flocculant and you see the particles begin to floc, but they don’t floc enough to sink to the bottom, you can’t just top your water up with more flocculant later. You’ll have to start the process over entirely because eventually the flocculant leaves the water. This means for optimal results; you need to hit the water all at once. So always have a little extra flocculant on hand.

Step 5: Applying the flocculant

The final step is to apply to flocculant to your dam water. We recommend using a canoe or boat and spraying the flocculant evenly across the water. After 10-15 minutes of applying the flocculant you should begin to see results. If not, add 10% more flocculant than you initially calculated.

If no reaction occurs, leave the dam to settle for 24 hours and assess the results.

Buy WaterTreats Flocculant from our e-store


Need expert help?

Need help determining whether a flocculant is right for you and how much you’ll need? Complete our Dam Diagnostics Survey. We provide free, no-obligation advice.