Quick Summary: A dry well for your outdoor sink is a simple, underground system that safely drains wastewater away from your home and garden. It’s an eco-friendly way to manage greywater, preventing muddy puddles and protecting your landscape. This guide will walk you through building one easily.
Ever set up a charming outdoor sink for your garden or patio, only to be faced with an unwelcome puddle after every use? It’s a common, frustrating problem! Water pooling around your sink can lead to muddy messes, attract pests, and even damage your plants if the water isn’t healthy. But don’t worry! Creating a simple dry well is a fantastic, eco-friendly solution. It’s a DIY project that’s easier than you might think and will keep your outdoor space looking tidy and beautiful. Let’s get your outdoor sink draining perfectly!
Why You Need a Dry Well for Your Outdoor Sink
An outdoor sink is a gardener’s best friend. Imagine rinsing your hands after planting, washing fresh produce straight from the garden, or cleaning muddy tools without trekking inside. But where does all that water go? If it just spills onto the ground, you can end up with swampy patches, especially after frequent use. This is where a dry well shines!
A dry well, also known as a “soakaway pit” or “recharge pit,” is basically a hole in the ground designed to collect and slowly release water into the soil. For an outdoor sink, it’s especially useful for managing “greywater” – the water from sinks, showers, and washing machines that is relatively clean. This greywater can even be beneficial for your plants if you’re not using harsh chemicals. Properly managing this water prevents:
- Muddy Areas: No more soggy spots that attract mosquitos and make walking unpleasant.
- Erosion: Water directed onto a slope can wash away soil. A dry well helps disperse it gently.
- Damage to Foundations: Constant moisture near your home’s foundation can cause problems.
- Unpleasant Odors: Stagnant water can start to smell.
By installing a dry well, you’re not only solving a practical problem but also making a smart choice for your property’s health and your garden’s well-being. It’s a sustainable step towards loving your outdoor living space even more.
Understanding Greywater and Your Outdoor Sink
Before we dig into building, let’s chat about the water itself. The water coming from your outdoor sink is typically considered “greywater.” This is different from “blackwater,” which comes from toilets and contains human waste. Greywater is generally safe to be used for irrigation or disposed of through a dry well, provided it doesn’t contain harmful chemicals or excessive grease.
For an outdoor sink, you’ll likely be washing off dirt, garden produce, or your hands. If you use natural soaps and avoid harsh chemicals, the water is even more garden-friendly! Many eco-conscious homeowners are exploring ways to reuse greywater from sinks and showers for landscape irrigation. A dry well is a key component in safely managing this water when direct irrigation isn’t feasible or desired.
Things to consider for your outdoor sink water:
- Soaps and Detergents: Opt for biodegradable and plant-friendly options. Avoid soaps with bleach, boron, or high levels of salt.
- Grease and Food Scraps: Try to avoid letting large amounts of grease or food particles go down the drain. A simple mesh strainer in your sink’s drain can catch most debris.
- Proximity to Water Sources: Ensure your dry well is located a safe distance from wells, septic systems, and natural bodies of water to prevent contamination. Local regulations often specify these setback distances. You can check with your local environmental health department or building authority for specific guidelines. For example, the U.S. Environmental Protection Agency (EPA) provides general information on groundwater contamination.
By being mindful of what goes down your outdoor sink, you can make your dry well an even more sustainable and beneficial feature for your yard.
Types of Dry Wells for Outdoor Sinks
When it comes to dry wells for smaller applications like an outdoor sink, you have a few main options. The best choice for you will depend on your soil type, the amount of water you expect, and how much space you have. Here are the most common types:
1. Gravel-Filled Dry Well
This is the most traditional and often the simplest DIY type. It involves digging a hole and filling it with gravel. The gravel creates empty space, allowing water to infiltrate the surrounding soil.
How it works: Water overflows from the sink drainpipe into the gravel-filled pit. The larger surface area created by the gravel allows water to soak into the soil more quickly than it would on a bare patch of ground.
2. Chamber or Basket Dry Well
These are often pre-manufactured plastic chambers or baskets designed specifically for water infiltration. They offer a larger storage volume and higher infiltration rates than a simple gravel pit of the same size.
How it works: The chamber is buried, and the sink drainpipe empties into it. The chamber itself is porous or has perforations, allowing water to seep out into the surrounding soil. These can be more efficient and require less excavation than a gravel-filled pit for the same capacity.
3. Dry Well with Geotextile Fabric
This method involves creating a pit, lining it with a permeable geotextile fabric (landscape fabric), and then filling it with gravel or other inert materials. The fabric prevents soil from clogging the gravel while still allowing water to drain.
How it works: The fabric acts as a barrier, keeping the gravel clean and ensuring long-term effectiveness. It’s a good practice to include with any gravel-filled dry well to maintain its permeability.
Choosing the Right Type
For most beginner DIY projects involving an outdoor sink, a well-designed gravel-filled dry well lined with geotextile fabric is often the most accessible and cost-effective choice. Chamber systems are excellent but can be pricier. Your soil’s percolation rate (how quickly water drains through it) will also influence performance; sandy soils drain faster than clay soils.
Planning Your Dry Well Project
A little planning goes a long way to ensure your dry well works perfectly and avoids any potential issues. Let’s get you ready!
1. Assess Your Site
Before you grab a shovel, take a good look at the area around your outdoor sink. You need to find a suitable spot for your dry well.
- Drainage Needs: Where is the water currently going? Where do you want it to go safely away?
- Soil Type: Is your soil sandy and drains well, or is it dense clay? You can do a simple drainage test (explained below).
- Slope: Avoid locations that collect water naturally. Ideally, the dry well should be downslope from your sink.
- Regulations: Check with your local building department or environmental agency for any rules about dry well placement, size, or type. This is crucial! Some areas have specific setback requirements from property lines, wells, or septic systems. The EPA also offers guidance on decentralized wastewater systems which can be helpful background.
- Underground Utilities: VERY IMPORTANT! Call 811 (in the US) or your local utility locating service before you dig. This is a free service that will mark underground lines like gas, electric, and water, preventing serious accidents.
2. Size Your Dry Well
The size of your dry well depends on how much water your sink will produce and your soil type. As a general rule of thumb for sinks that aren’t used constantly, a dry well about 2-3 feet in diameter and 3-4 feet deep is often sufficient.
Drainage Test (Percolation Test):
- Dig a test hole about 1 foot deep and 1 foot wide.
- Fill the hole with water. Let it soak in completely.
- Fill the hole with water again.
- Time how long it takes for the water level to drop one inch.
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If it takes less than 1 hour: Your soil drains well, a standard dry well should work.
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If it takes more than 2 hours: Your soil drains slowly. You might need a larger dry well, a dry well with baffles, or a different system altogether.
For an outdoor sink producing less than 50 gallons per day, a simple gravel-filled pit should be adequate. If you’re concerned about volume, err on the side of slightly larger.
3. Gather Your Materials and Tools
Having everything ready before you start makes the process smooth. Here’s a list of what you’ll likely need:
Tools:
- Shovel (round-point for digging, spade for edging)
- Trowel (for finer work)
- Level
- Measuring tape
- Wheelbarrow (for moving soil and gravel)
- Gloves and safety glasses
- Hole saw or PVC pipe cutter (if modifying existing pipes)
- Sledgehammer (optional, for breaking up tough soil)
- Tape measure
Materials:
- PVC pipe (4-inch diameter is common for drain lines)
- PVC elbow (if needed to connect sink drain to pipe)
- Geotextile fabric / Landscape fabric (permeable)
- Gravel (crushed stone, pea gravel, or 3/4-inch clean aggregate) – calculate about 1.5 cubic yards for a 3ft dia x 4ft deep hole.
- A block of wood or a large flat stone (to prevent overflow pipe from collapsing)
- Optional: Pre-made dry well chamber (if choosing this option)
- Optional: Fine mesh screen or filter for sink drain
Always get a bit more gravel than you think you’ll need, as it’s always better to have extra!
Step-by-Step Guide to Building Your Dry Well
Let’s get digging! This process is designed to be straightforward for beginners. Remember to wear your safety gear!
Step 1: Mark Your Dry Well Location
Choose a spot that is downhill from your sink, at least 5-10 feet away, and clear of any underground utilities (after calling 811). Mark the approximate center of your intended dry well area. A circle about 3 feet in diameter is a good starting point.
Step 2: Dig the Pit
Begin digging a hole at your marked spot. Aim for a depth of 3-4 feet. The diameter should be around 2-3 feet. As you dig, place the soil in your wheelbarrow or on a tarp. This soil can be used to backfill around the dry well later, or for other garden projects.
Tip: For easier soil removal, try not to dig the pit perfectly vertical. Slightly sloping sides are easier to work with and more stable. Also, consider that you’ll be adding gravel and potentially a pipe, so the pit needs to be larger than your final underground structure.
Step 3: Prepare the Sink Drain Outlet
You’ll need to connect the drainpipe from your outdoor sink to the dry well. This might involve extending an existing drainpipe or running a new one. If you have a simple gravity drain from the sink, gently guide a 4-inch PVC pipe from the sink’s drainage point to the edge of your newly dug pit.
Important: Ensure the pipe slopes slightly downwards from the sink to the dry well so water flows by gravity. Use an elbow fitting if needed to direct the pipe into the pit.
Step 4: Line the Pit with Geotextile Fabric
Lay your permeable geotextile fabric over the bottom and up the sides of the pit. Overlap the edges by at least 6 inches. This fabric is crucial for preventing soil from clogging your gravel and reducing the effectiveness of the dry well over time. Trim any excess fabric, but ensure it completely covers the soil.
Step 5: Add a Layer of Gravel at the Bottom
Pour a 4-6 inch layer of gravel at the bottom of the fabric-lined pit. Spread it evenly. This provides a drainage base.
Step 6: Position the Overflow Inlet Pipe
Carefully guide your PVC drainpipe into the pit, so it sits about halfway up the planned depth of the gravel fill, or slightly higher. You want the water to fill the gravel around it before it exits.
Stabilize the Pipe: To prevent the pipe from collapsing under the weight of the gravel or being dislodged, place a flat stone or a sturdy piece of wood directly beneath it where it enters the pit. This acts as a support.
Step 7: Fill the Pit with Gravel
Now, fill the rest of the pit with gravel, all around and over the inlet pipe. Leave about 6-8 inches of space between the top of the gravel and the ground level. This space is important for allowing surface water to drain in and preventing soil from washing directly into the gravel.
Step 8: Fold and Secure the Fabric
Once the gravel is in place, fold the sides of the geotextile fabric back over the top of the gravel. Secure it with a few small stones or garden staples if needed, ensuring it remains snug.
Step 9: Backfill Around the Pit (Optional but Recommended)
If you have extra soil from digging the pit, you can use it to create a slight berm or mound around the perimeter of the dry well, sloping away from the dry well. This helps direct surface water away from the dry well opening and prevents it from becoming a pooling spot itself.
Step 10: Reconnect and Test
Connect your sink drainpipe to the inlet pipe. Run some water through the sink. Watch and listen to ensure the water flows freely into the dry well and that there are no leaks in the piping. Check the dry well area to make sure water is soaking into the soil as expected.
Congratulations, you’ve built your very own dry well!
Dry Well Maintenance and Best Practices
While dry wells are generally low-maintenance, a little care ensures they work effectively for years to come. Think of it as giving your garden’s drainage system a little love!
Regular Checks
- Listen for Flow: When using your sink, do you hear the water flowing freely into the dry well? Any gurgling or slow drainage might indicate a problem.
- Inspect the Sink Strainer: If you added one, clean it out regularly to prevent debris from entering the drainpipe and potentially clogging it.
- Observe the Area: After rain or use, does the ground around the sink stay dry? Are there any signs of pooling water above the dry well?
What to Watch Out For
Clogs: The most common issue is a clog developing in the inlet pipe or a buildup of fine sediment in the gravel over many years. If drainage slows significantly, you might need to clear the inlet pipe or, in extreme cases, excavate and replace the gravel.
Soil Compaction: Avoid heavy foot traffic or placing heavy objects directly over the dry well. This can compact the soil and reduce infiltration.
Eco-Friendly Usage Tips
- Biodegradable Soaps: Continue using eco-friendly soaps and cleaners. This protects not only your dry well but also the surrounding soil and plant life.
- Filter Debris: Always use a sink strainer to catch food particles or large debris before it goes down the drain.
- Monitor Use: If your outdoor sink is used very frequently or for prolonged periods, be aware of the cumulative water volume. In very wet periods, the dry well might fill up faster than it can drain.
By following these simple practices, your dry well will continue to be a helpful and sustainable feature of your outdoor space.
Pros and Cons of an Outdoor Sink Dry Well
Like any project, understanding the benefits and potential downsides helps you make the best decision. Here’s a quick look:
| Pros | Cons |
|---|---|
| Prevents Mud and Puddles: Keeps your outdoor area clean and usable. Good for aesthetics and preventing pest issues. | Requires Digging: Installation involves excavation, which can be labor-intensive. |
| Protects Landscaping: Avoids waterlogging and root rot for nearby plants. | Potential for Clogging: If not properly filtered, debris or
 |