What to Do When Concrete Blocks Drains


Blocked drains are a common problem for homeowners, but some blockages are harder to fix than others. If concrete or cement becomes lodged inside a pipe, it’s important to act quickly. Depending on the scale and severity of the blockage, it could cause the pipe to burst and flooding will ensue.

Most people assume that drain replacement is necessary when a drain is blocked by concrete or other solid materials, but this isn’t always the case. In some instances, it may be possible to unblock the drain and prevent damage from occurring.

What Happens When You Pour Concrete Down A Drain?

If you pour concrete down a drain at a rapid pace, there’s a good chance it will cause a full-scale blockage quickly. Depending on how much concrete is present, the entire drain may become blocked. Although this can be disastrous for homeowners, you will be aware of the problem relatively quickly. As fluid will be unable to travel through the drain, flooding is likely to occur.

In most cases, pouring concrete down a drain doesn’t cause an immediate, full blockage. Instead, the concrete coats the inner sides of the drain and reduces its diameter. Once the concrete reaches a bend in the pipe, it will settle at the bottom and restrict the flow even further.

As concrete hardens, it begins to set and this can then cause damage to the pipework. Most modern drains are constructed from plastic, so set concrete is quite capable of cracking the pipework or causing it to shatter. At this point, the drain becomes unusable and any fluid that attempts to pass through it will simply leak into the surrounding area.

Even if the concrete sets without causing extensive damage to the drain, it could still result in long-term problems. The narrowing of the drain will prevent your pipework from functioning optimally, which reduces the flow speed and increases the likelihood of subsequent blockages.

Removing Concrete from Drains

If a small amount of concrete has been inadvertently poured down an external drain, the pipework may be salvageable. Powerful drain jetting can be used to break down smaller and moderately sized concrete blockages. By breaking the concrete down into smaller pieces, it can be moved through the pipework without causing any damage.

If the blockage is too large for drain jetting to be used in isolation, specialist chemicals can be added to facilitate the breakdown of the concrete. This is predominantly used when larger build-ups mean that drain jetting alone will be ineffective, but damage has not yet occurred to the pipe.

If you really want to avoid the need for a drain replacement but chemically assisted drain jetting isn’t effective, it may be possible to use professional tools to cut and remove the concrete. With the assistance of a CCTV drain camera, specialist technicians can manually cut through the concrete to break it up. As a no-dig solution, this ensures concrete can be completely removed without the need to excavate pipework and lay new drains.

When is Drain Replacement Necessary?

If the pipework has been irretrievably damaged by the concrete, drain replacement may be your only option. Similarly, if concrete cutting or chemically assisted drain jetting fails to remove the blockage, a replacement drain may be needed.

Although most homeowners dread the thought of drain replacement, it needn’t be as complicated or messy as you think. Providing you hire reputable contractors and specialist technicians; the project can be completed quickly and with the minimum of hassle.

When concrete blocks drains, it typically affects exterior pipework. This is because concrete mixing usually takes place outside, rather than in your home. Fortunately, this means that interior pipework is rarely affected by concrete blockages and can be left in place. While excavating an external pipe isn’t a job any homeowner wants to have to do, it does mean that interior décor and features will remain entirely unaffected.

Preventing Concrete Blockages

It may be tempting to dispose of concrete and other building materials using your drainage system, but this is never a good idea. At best, you’re going to damage the functionality of your drains and, at worst, you’re going to cause immediate and serious damage to both your drainage system and property.

However, homeowners aren’t always aware of the risks or may inadvertently pour concrete down drains. When this happens, acting quickly and contacting specialist drainage technicians is the fastest and most effective way of resolving the problem and preventing permanent damage.


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