Easy to build flood and drain system

Have you checked the prices of flood and drain systems? These sell for hundreds of dollars, but this is wasted money since they are so easy to build at home. Okay, one thing was a little complicated. I had to re-thread the water bottles I used. This wasn’t that complicated, but it does require a threading die to complete. Harbor freight sells these for a few bucks. The quality isn’t the greatest, but since we’re only threading plastic, no big deal.

In previous posts, I have demonstrated drip systems. These can be as simple as a finished systembucket, basket, and pump, or as elaborate as your heart desires. Drip systems are easier, but flood and drain has much less maintenance. And since the pump cuts on a few times a day, it uses less electricity.

A flood and drain system (sometimes called ebb and flow) can be employed in several ways. One way is to create a water sealed top container and a lower reservoir. The water floods the top container, and then drains back down to the reservoir. If you choose to use a large container, you’ll also need a bigger reservoir. There has to be enough water to fill the container and enough excess to keep pumping throughout the flood cycle. It isn’t less complicated than what I’m going to demonstrate, and it takes up much more room. I’m using a fold out table in my basement. I don’t want the weight of 30 gallons of water on my table. Plus, I want to keep the reservoir small enough to not take up all my floor space. The inset picture above gives you an idea of the finished product.

I’m using PVC pipes, a five gallon bucket, and used plastic water bottles. Here is a list of the materials you’ll need for a twelve station flood and drain system:

lay out– One or two, 3/4” PVC pipes.
– 6 each – 3/4 elbow – one end threaded, the other a slip on fitting.
– 6 each 3/4 T connectors, top end threaded.
– 1 each 3/4 T connector – all connectors slip ons.
– 2 each cross connectors, 3/4 slip on connectors.
– 1 each 3/4 slip on x 1/2 threaded 90 degree elbow.
– 1 1/2 flex hose, threaded male connectors on each end. Usually found in the irrigation department.
– 1 each 5 Gallon bucket with lid
– 1 Air Pump with stone and hose
– 1 Submersible Water Pump. Must be one that doesn’t have a backwash safety. You want the water to drain when the pump stops.
– 12 Plastic water or soda bottles.

If you don’t mess up or if you build a smaller setup, you can get by with one pvc pipe. I made this up as I went, so keeping a little extra on hand is always a good idea. A four station setup would only need a fraction of the materials, but since I had twelve lettuce plants in waiting, a decided on a twelve station setup.

I carved up the PVC pipe to fit my design. The main pipe consists of two 11” pipes. The two pipes connect with a 4-way cross connector. On each end they connect to a slip on T-connector.

Be sure and do a dry connection first. Don’t glue until you’re ready for final assembly.

Cut six 3” pipes to connect to the main feeding pipe. Cap them off with a T-connector facing upward. The upward connector should be threaded.

Cut five 5-1/2” pipes. These don’t have to be precise – unless you are OCD. If that’s the case, this blog will stress you out. The reason you aren’t cutting six is because one feed will have an overflow pipe connected to it. We’ll do that one last.

Connect each pipe to the T-Connectors and cap them off with a 3/4” elbow – threaded on the upward end. The upward pointing connectors will hold the pots / bottles. You’re dry run should look something like below.

lay out

The 4-way cross connector will need a 3 to 4” pipe attached to an elbow pointing downward. This will feed into your reservoir. The feeding pipe will be cut to fit based on the height of the table you are using.

At this point you can either make this an 11 station system, extend the overflow section out to be longer than the rest of the piping, or move two planters closer together. I chose to move mine together. See below:


Cut a 3” pipe. Connect one end to the 4-way cross connector. The other end goes into a slip in T-connector. All three connections are slip in. The top connector is for the overflow pipe.

Let’s take a moment to talk about the overflow pipe. The purpose of this pipe is to keep your containers from flowing over. As the water rises in the containers, it also rises in the overflow pipe. You want the pipe to be engaged just before the containers reach the capacity you desire. In my case, I chose to set the overflow to begin about 2” from the top of my containers. The bottom of the inside diameter of the pipe should then be two inches below the top of these containers.  When the water reaches this point, it will begin flowing into the overflow and back into the reservoir. The water is under pressure from the pump, so you must allow a little extra space at the top. Some planters will fill a little higher than the overflow – but not much higher.

An accurate overflow is essential for a flood and drain system. Too low and the roots of the plant will be dry. Too high and your table will be wet.

Eyeball the correct height, allowing for the added distance of the elbow, and cut a pipe to fit. Make certain that all your planters are the same height. Cut a second pipe for the return flow and add another elbow to direct the pipe back down to the reservoir. Here is my finished overflow.


If you are planning to reduce the planters by one, you can cut another 5-1/2” pipe, or if you want two planters close together, cut two pipes to the necessary length. As you can see from my picture above, I changed my mind and added another planter.

Now let’s prepare the planters. I chose to use water bottles since my plants will be fairly small. I plan to make this a lettuce garden. When choosing a water bottle, look for quality. Don’t get a cheap, flimsy bottle, but get the thickest one you can find. Especially watch for the depth of the cap. The cheaper brands have short caps. This will not give you enough surface to glue.

Herein lies a new problem. PVC pipes have a 3/4 inch connector with 14 threads per inch. Water and soda bottles do not have the same threading pattern. They will not fit correctly in a pvc connector. Some people glue the caps into a wider connector, but that adds to the expense and still has trouble making a good seal. Instead, I’ve chosen to sand off the threading and rethread the bottle tops. This only takes about 5 minutes per bottle.

The easiest way for me is to press the bottle against a belt sander and rotate it until all the grooves are gone.
sanding bottle

There should be no smooth plastic or protruding grooves when you are done. Before ending your fun on the sander, taper the end of the bottle to make it easier to feed into the threading die. You’ll be glad you did.
sanded bottle

Now rotate as you feed the bottle lip into the threading die. It will take a little force and don’t be surprised if you don’t go in straight the first time. Keep working it until you are flush against the rim of the bottle and the die. When you unscrew it, you’ll have a nicely threaded bottle lip.
thread bottlethreaded bottle

Now you are ready to glue the bottles into the PVC connectors. But before you do, cut off the bottom of the bottles.

cut bottle

I chose to cut in the last groove. It makes it easier to insure all the bottles are exactly the same. Now prime, glue, and paint.

glue bottle

Priming is important, for it helps the PVC glue to make a good seal. You want to prime all of your connecting parts and let them dry before gluing. Very important.

Here is the painted and glued bottles.

glued bottle 1glued bottle 2

I painted the bottles first, then glued them into the connectors, and then glued the connectors into my pipes.

Painting the bottles is important because it keeps light out, which keeps algae from growing. You will be feeding the plants with a nutrient rich solution. If it will grow plants, it will grow algae. Slimy algae. You don’t want an eco-system that includes anything but what you introduce.

Use a paint that is designed to coat plastic. This is in abundance at local hardware stores. You may be wondering why I chose a beige paint instead of black or white? There is a scientific explanation behind using beige. It was the only color I had lying around.

Lay the pieces on a flat surface and begin gluing the parts. PVC cement sets quickly, so act fast. Glue and align. If you goof something up, the only thing you can do is cut it off and repair it with pipe pieces and connectors. If you look at the left middle in my picture above, you can see that I had such an experience. I had to add an extra connector to extend it out and repair my mistake. Mistakes are a part of life – especially when you build by the seat of your pants.

Next, place the bucket where it will be residing and measure off the pipes. The overflow isn’t an exact science. You need to make sure it extends well below the lid so the water doesn’t splash out, and it needs to be above the water line to insure the overflow comes through without resistance.

Keep in mind that a lot of water will be in the containers during pumping, so unless your pipe is more than halfway to the bottom of the bucket, it’s doubtful this will be a problem.

tank top

Cut three holes in the bucket lid. Two to match the pipes and one for the power cord and the air hose. Here is the final setup. I have an air stone inside. This is vital. Let me emphasize this again. Aerating your water is *VITAL*. Otherwise, the water will stagnate and things will begin to grow. Nasty things. Things that like to attack plant roots and smell up the water.

inside tank

You may have noticed a valve with a red knob and said, “Hey. That wasn’t in the instructions.” To that I would say, “Nope. I haven’t mentioned that before now.”

When testing my system, I had an unexpected development. My pump pushes out too many gallons per minute for the overflow pipe to keep up with. Gravity can only move water so fast. The solution was to either buy another pump – one that had an adjustable outflow, or buy a $2 valve that could be adjusted to restrict the flow of water. I chose the $2 option. In this setup, the flex riser goes into the valve and slows down the water leaving the pump.

The normal setup would be to have the 1/2” flex hose (riser) screw into the top of the pump and then to the 3/4 x 1/2” threaded elbow. Instead I had to add a 1/2×1/2 male connector into a valve of the same measurements. Then the flex hose screws into the other end of the valve. If you’re buying a new pump, just get a controllable outflow pump. It’s basically the same price as one that doesn’t have it, so it isn’t necessary to do what I have done here.

I did one last thing for safety purposes. I used epoxy repair putty around the base of my planters. This insures a good water seal to prevent leaking. It’s an extra step that may not be necessary if you glued thoroughly, but I have a phobia of leaking hydroponic systems.

Buy a mechanical timer. I bought mine at Harbor Freight for $2. Many grow stores carry them for around $15. Make sure you get the kind that have push tabs. This is very important for flood and drain. When the tab is up, it activates the power. When down, it cuts it off. Connect this to your water pump, but not to the air pump. Air should always be running.

After everything has been fully assembled and in place, allow everything to dry overnight. Then fill up the bucket with 4 gallons of water and let it flood and drain for 24 hours. Set the tabs to turn on for 15 minutes every hour. This is to get glue and residue out of the pipes. Empty the water and refill with 4 gallons. Set the tabs on your timer to turn the pump on for 15 minutes every three hours. Now you are ready for horticultural adventure!

Below is my setup after transplanting my lettuce.
with plants

In a few weeks I’ll have to find a new home for my Jade plants and Carnivorous plants.

If you’re using the FloraDuo nutrient solutions, add 3 teaspoons of ‘A’ and 1 teaspoon of ‘B’ per gallon of water. If you are using the same setup as I am using, that would be 12 tsp. of A and 3 of B per four gallon water change.

I’m growing lettuce, so I adjusted the PH to 6.1. Keep an eye on the water level, keeping in mind that some of the water will stay with the plant. For young plants, change the water once a month. When in full growth mode, change once a week.

In my above pictures, I transplanted my seedlings into Sure To Grow. It doesn’t have capillary action, so the top will remain dry and algae free.

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Eddie Snipes 2012
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Build a Flood and Drain system (Video)


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