If you have a permanently damp area in your yard, or you find water constantly in your basement after every heavy rain or snow, there’s a solution–a French drainage system inside or outside your home will help. It’s critical that you have a good drainage system to ensure that your house stains mold-free and dry. If your have groundwater collecting somewhere in your basement, not only can it be a problem, but it can also cause rot and mold on any wood parts of your basement.
In this guide, we’ll outline the basics of French drain cleaning to ensure that your system works as it should. We’ll also touch on the do’s and don’ts of French drain usage and maintenance, and more below.
French drains are very popular to help funnel water away from your home to protect the foundation, but you have to maintain them to keep them in good working order.
Defining a French Drain System
An outdoor French drain system is a trench that you cover with rocks. You connect it to pipes to help guide water away from your home’s foundation. The first portion of this system is elevated or has a higher end, and this is called the drain field. The drain field is where the groundwater or any excess surface water enters your drainpipes. Then, the second portion of this system is the exit point. This is the lowest point in the system where the water leaves the drain.
A French drain offers you a great solution if your basement is leaking water in through the foundation. In a “wet” basement setup, the water pressure against the foundation will slowly leak through. However, a French drain will work to reroute the water near the foundation and release it out into the yard.
If you’re still finding water in your basement even though you have enough outdoor drainage, you may need to consider an interior French drain system. To do so, you’d cut a trench in your basement slab right along the foundation’s perimeter, lay pipe in this trench and put in a sump pump to help move the water out of your basement and outside.
You also have the option to install a pipeless French drain system. A pipeless French drain doesn’t have pipe, as the name suggests, but it has more internal resistance to the natural flow of water. So, it can’t evacuate nearly as much surface water as a traditional setup can.
How French Drains Work
Water will always find the lowest point along the most straightforward path, and it’ll readily move into empty pockets in loose soil. This is where this setup comes in, and it’s part of the reason why it’s so important to learn how to go about French drain cleaning. It provides an easily accessible path and creates a slightly sunken channel, and this encourages water to drain out of the soil and to flow along a smooth course.
For your system to work correctly, it has to leverage gravity as it first starts to force the water down from the surface from the saturated soil. It’ll pull it along the downward-sloping pipe to the correct discharge point. Ideally, you want to slope the tench bottom around an inch for every eight feet in the direction you want the water to flow. Depending on your circumstances, you can divert the water into a:
- Drainage ditch
- Dry well
- Low-lying spot on your property
A very simple way to decide where to install your system around your home is to look for any area where your water pools, especially if the water sits for hours or days after any rain event.
How to Tell If the French Drain Is Working
The easiest way to tell if your French drain is working and you don’t have to do anY French drain cleaning is to look at your basement or lawn. If you see water, chances are, there could be a problem and your drain isn’t working right. This issue could be due to a clogged drain.
When water starts to seep through the soil to get to your French drain, it usually brings sediment to the drain, where it dumps the sediment in the drain on the gravel as it flows into and through the trench you dug. The sediment will gradually build up over time and slow how quickly the water flows through the drain. It could even eventually block it completely. When this happens, the water won’t be able to pass correctly through the drain. In turn, this could cause your yard or basement to flood.
Another way to tell if you have a French drain system that is working correctly is to call in a professional to take a look. They can let you know if there’s any worrying buildup that can turn into a clog unless you address it.
One of the best ways to tell if it’s time for French drain cleaning or not is to look at your yard. If you can see puddled water or damp ground where it’s not supposed to be, this is an indicator that your system isn’t working.
French Drain Cleaning – How to Unclog the System
To keep soil from building up in the pipe that will eventually stop water from flowing out and in, you need to have a routine in place for French drain cleaning. A clogged interior French drain can result in water backing up into your basement. If you have a clogged exterior French drain, water will start to back up instead of draining properly out into your yard. If you have a clog, you have to take steps to fix it, and we’ll outline them below.
Step 1 – Find the End of the French Drain
You’ll see a hole in the ground where your French drain system’s end starts. If you’re not certain where your drain starts, you want to try looking at the highest point of your yard. This is because the whole design of the drain is supposed to help the water run downhill.
Step 2 – Run Water Down Your French Drain
Grab your garden hose and use it to run water down your French drain system. If you notice that the water is backing up instead of flowing out, this means that you have a clog in your system.
Step 3 – Unclog the Drain with a Pressure Washer
As part of your French drain cleaning process, you want to unclog it periodically. To do so, get a pressure washer and use a jet of high-pressure washer to send water down your drain. When you do this, you want to stand off to the side because the water could end up coming back out at you once it first hits the clog. Aim the high-pressure stream of water at the bottom of your French drain to eject the clog. Moving the spray around, carefully clean out the insides of the pipe.
Step 4 – Remove Stubborn Clogs With a Sewer Snake
A snake is a longer piece of piping that you will stick down the French drain to help reach the clog. Gently push the clog with the snake to try and make it break free. If it breaks free or feels like it’s looser, swap back to using the pressure washer to make sure you break up and get rid of the whole clog and push it down the drain. You’ll keep using both the sewer snake and pressure washer until you see water flowing freely down the drain.
French Drain Maintenance
The good news is, there’s not a lot of regular maintenance you’ll have to do to your system to keep it working properly. However, as time goes on, leaves and debris can build up in the holes of your drainpipe, and this will compromise how effective it is. To prevent this from happening, clean out and snake your French drain once a year.
No matter if you’re performing routine French drain cleaning on an interior or exterior setup or taking steps to maintain it, you’ll need the help of an electric sewer snake. You can typically rent one from your local home improvement store if you don’t want to buy one. If you want to buy it, you can do so online or at a hardware store.
Snaking the Drain
For routine French drain cleaning, the following are the steps you’ll take:
- Before you start your French drain cleaning project, put on a pair of leather work gloves. These gloves will help protect your hands from becoming cut or torn up as you feed the snake’s cable into the drain.
- Carefully uncover the drain’s lid. If the French drain attaches to your gutter downspout, you’ll have to remove this downspout from your drain’s entry point.
- Turn your electric drain snake on and feed the cable into your French drain.
- When the snake cable hits the clog or obstruction or a turn in your drain, you want to hold it back as the snake turns into the pipe. Once it gets through the turn in the drain or clog, feed it gently into your drain.
- Keep feeding the cable into the drain until it gets to the other side. Let the snake turn inside of your drain when it hits resistance from clogs, tree roots, or other obstructions. When you finish, retract the snake and feed it back into the device.
- Once you finish, get a hose and put it in power jet mode to spray water into the drain using your hose to push out other obstructions or debris.
Snaking the drain is one way to help get rid of stubborn clogs that the pressure washer can’t get rid of.
Dos and Don’ts of French Drain Cleaning
A French drain system can do wonders to help with a damp basement by keeping water from going through the foundation and soaking the space inside. No matter if you install them outside or inside, they use plastic pipes with holes drilled into the bottom to collect rain and send it downhill. This will remove the water before it can cause damage to the home.
But, just like any drain system, your French drain is prone to clogging. Debris and soil will slowly build up inside of the pipes, and this will eventually get thick enough to stop the water from flowing. To avoid letting the water back into your home, French drain cleaning is a must, and the following do’s and don’ts will ensure you do it correctly.
DO Inspect the French Drain
Even if you want to just do annual French drain cleaning and maintenance, most experts recommend that you assess the condition of your drain first. You can test the drain by flooding it to see how it handles a large volume of excess water. The first step requires finding out where the ground-level access point for your drain is.
Generally speaking, this is usually a grate that sticks up above the ground, a pipe above the ground, or your gutter downspout. Remove the fitting or cap and run a hose down your pipe. Most systysm that are in good condition will be able to handle the volume of water from a hose. If the water backs up, this means there’s an issue with the drain, and it’s usually a clog or blockage.
DO Use a Pressure Washer to Clean the Drain
The easiest and gentlest way to go about French drain cleaning is to use a pressure washer. These handy tools come with onboard pumps that take standard water pressure and dial it up to force it to go into tiny orifices at the end of the wand. It’s recommended that you do this annually, and it’s an easy method that won’t damage the pipes.
All you have to do with this method is place the nozzle in the pipe and blast some water toward the clogged area. It helps to change the angle of the pipe if you can. If the clog isn’t too solid, a pressure washer can break it down slowly until the water can push the rest of the clog out and clear the drain.
This method is most helpful when you spray the clog near the end of the French drain to give it unimpeded access to the pipe. If you’re spraying from behind the obstruction or clog, the pipe can fill with water before it clears it out.
DO use a Heavy-Duty Snake to Clear Stubborn Clogs
Pressure washing is a light-duty French drain cleaning option that won’t damage the pipes, but it’s usually not enough to clear out stubborn clogs, and neither are drain cleaners. Plant and tree roots, compacted soil or mud, and even small rocks can eventually create a barrier that a pressure washer can’t break though.
For these tough clogs, you need a heavy-duty drain snake. These machines come with powerful motors that work to spin a steel cable with a claw at one end. This will break up anything that gets in the way, but it does it slowly. You can rent this machine at most tool rental locations, and they have the power to break through heavy-duty clogs. All you have to do is explain how you want to use this machine, and the rental clerk can recommend the best head or claw for the job.
DO Inspect the Surrounding Area for Obstructions or Issues
Not all French drain cleaning issues are caused by clogs inside of the pipe. This is why it’s also important to check around the system to spot potential problems. Potential issues can include clogs above the pipe from compacted soil and thick sediment layers that prevent water from getting to the weep holes in the pipe.
Nearby trees can also send roots over or under the pipes, and these roots can change the pitch of the pipe, separate connections, and cause other problems. If you notice roots near the surface of the soil, heaving, or sinking of the ground, it may be a good idea to take a much closer look at the ground below it.
Performing routine French drain cleaning and maintenance can help prevent huge problems down the road and ensure that your foundation or yard stays dry.
DON’T Ignore a Clog in Your French Drain
There are several reasons why your French drain may have a clog somewhere in the pipe system. The weep holes in the bottom of the pipe are larger, and this allows for the best groundwater flow possible. However, this also means that they don’t filter out mud and sediment. Also, tree and plant roots can work into the pipe. Wherever is causing the clog in the system, it’s essential that you don’t ignore it.
If your home already had a French drain system in place when you moved in, you may not be able to appreciate all it does. French drains are only installed on properties that are prone to having water or flooding issues. These systems collect water and move it away from the foundation so it won’t penetrate the basement walls. If it does, it can easily cause mold, dampness, structural damage, or bigger issues. This is why it’s so important to have routine French drain cleaning in place.
DON’T Stand Over the Drain Opening While You Clean It
No matter if you’re spraying a hole in the ground or up a pipe, it’s a great idea to keep clear of the end of the drain. A pressure washer won’t remove a solid clog right away, so there’s a very good chance that the pressurized water will shoot down the pipe, hti the clog, and come flying back up and out the pipe toward you if you happen to be standing there. The water will come out dirty, so you really don’t want it to hit you.
For this reason, you should stand off to the side of the pipe, and it’s a good idea to put on a pair of safety glasses to protect your eyes from splashes and sediment. Also, don’t put your hand by the end of the nozzle because this is where the pressure orifice is, and it’s powerful enough to cut skin and cause damage to your nerves.
DON’T Rush When You Use the Drain Snake
Snakes can be very powerful tools, and they can be dangerous if you don’t use them correctly. They can wrap around your hand and cause a potentially serious injury, and the claw can unpredictable flail around when it’s out of the pipe. Also, always wear leather gloves and eye protection when you have the drain snake out to help with your French drain cleaning.
For these reasons, you don’t want to rush when you use this tool. When the drain snake hits an obstruction or an elbow fitting, it will feel like you can’t make it go any further. However, all you have to do is back the snake off a little and gently push it forward. You want to take your time and allow it to go through the elbow fitting or clear the clog. Once the drain snake comes through the obstructions, the drain will clear.
Four Ways to Check Your French Drain’s Status
A clogged French drain system won’t direct water away from the home. The excess water can lead to leaks, flooding, and property damage. If you suspect your French drain has a clog, the following four ways are how you check for it:
Look for Standing Water
French drains come designed to collect rainwater and make it flow downhill. If surface water is standing in lower spots in your yard that are supposed to flow into the French drain, you have a problem with drainage. If the lower areas of your yard are as dry and firm as the higher ones, your system is working as it should be.
- If the ground is boggy, flooded, or squishy, the system isn’t working correctly.
- Inspect any low areas in your yard that are supposed to flow toward the drain and see if they’re damp.
- A correctly working French drain should keep your low points as well-drained as the higher areas in your yard.
Excessive standing water or marshy soil is one of the first warning signs that you should check for when you start inspecting your French drain system. If you see this, it’s time to do a French drain cleaning.
Check for Flooding in the Basement
In many instances, French drains get installed around the foundations of homes to prevent water from flooding in. In the basement walls are leaking, or if you see signs of mildew and mold in the basement, there is a good chance you have a clog.
- Check around the basement for moisture, wet walls, leaks, mold, and mildew.
- Water infiltration into your basement is a sign that you need to do French drain cleaning
If your French drain isn’t positioned correctly to protect your basement, or if you don’t have a basement in your home, ignore this tip and go to physically check your drain’s condition.
Inspect the Water Level in Your Drainage Trench
To see if your system is working correctly, pick a section of your drain and use a trowel or shovel to remove the gravel from the drainage trench until you can see the drain pipe. Is there standing water in the drainage trench where it shouldn’t be? Is the water actually flooding over the top of your pipe? If so, your French drain has a problem.
- Get a shovel and use it to remove the gravel from a section of your drainpipe. You have to be careful so you don’t accidentally damage the pipe or any landscape fabric around it.
- Look at the drain pipe and the surrounding gravel.
- If you see water standing in the drainage ditch or the water is coming up over the top of the pipe, the drain isn’t functioning correctly.
- If the gravel is relatively dry and you don’t see any standing water in the drainage ditch, then your drain is working as it should.
A French drain is a perforated pipe surrounded by gravel. As the floodwater starts to flow into the trench, it will filter through the gravel and go into the holes on the bottom of the pipe. The water then gets conducted downhill through your French drain. If the drainage trench starts to overflow or it’s full, you have a clog. This could be due to the holes getting clogged, sediment buildup, or tree roots.
Check Your Drain Termination Point
Finally, one of the best ways to figure out if you need to start French drain cleaning is to see if the water flows into the drainage ditch and out the end of the pipe. To check this, you’ll:
- Find the downhill termination point in the drain. This could be a pipe end or dry well that directs the water to flow into the gutter.
- Uncover the termination point if it’s below the ground level.
- Get an expandable hose to direct water into the drainage ditch between 10 and 20 feet uphill from this termination point.
- Give it one to two minutes for the water to level in the trench and rise to get into the drainage pipe.
- If the water starts to flow out of the pipe, it’s working as it should.
- If the water does not flow out of the pipe, you have a clog or obstruction.
This simple test will allow you to figure out how healthy your drain is and whether or not you have to perform French drain cleaning. You can use a few minutes to perform this check periodically.
A French drain system that isn’t working well or at all can be cleared by snaking the pipe or using a pressure washer. However, if the drain gets clogged on a regular basis, this is most likely due to incorrect installation. In some cases, you’ll have to reinstall your French drain while paying special attention to the proper materials to ensure that you have adequate slope to correct any drainage issues.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.