In this Instructable I will be showing you a simple and easy yet effective DIY self filling water bowl for your pets.

The water bowl at the base will hold a small amount of water while the upside down soda bottle will act as a reservoir to refill the water bowl with water when the level drops below the open end of the soda bottle. This works because when the open end of the soda bottle is submerged below the water level in the bowl no additional air is able to get up inside the bottle and take its place and is therefore unable to force any of the water out. When the water level in the bowl drops below the open end of the soda bottle air is able to get up inside the bottle, displacing the water and causing it to pour down and out into the bowl until the open end of the bottle is once again submerged. This way your simple pet water bowl will be able to last around 10 times longer without having to be refilled manually saving you a lot of hassle and ensuring that your pet always has a healthy supply of water available at any time.

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Step 1: WHAT YOU WILL NEED

For this Instructable you will need:

- Plywood Sheets (around 1 centimeter thick)

- 4/2 Plank Of Wood

- Dog Bowl (water bowl)

- 90 and 45 Degree Set Square

- Hand Saw

- Jig Saw

- Electric Hand Drill

- Empty Soda Bottle

- Spray Paint (optional)

- Large Hose Clamp (has to fit around your soda bottle)

- Wood Screws

- Marker

- Ruler

- Tape Measure

- Sand Paper (optional)

- Drill Bits

- Cutting Jig (optional)

Step 2: MEASURING AND CUTTING THE PLYWOOD

The first step in the construction of your self refilling water bowl is to measure and mark out two rectangular shapes on your sheet of plywood. One of these shapes will be for the base of the design and the other will be used for the back board. I managed to find a scrap piece of plywood lying around that was exactly 30 centimeters wide and around 50 centimeters long which suited perfectly for the base of my design and therefore didn't need to be cut to size. To make the back board I wanted to keep the width the same as the base board and have the height of it just a little bit taller than the height of the soda bottle that I was going to use (you will want to have it approximately 5 centimeters taller than the height of the soda bottle). I then went ahead and measured and marked out a 30 centimeter wide by 35 centimeter tall rectangular shape onto my plywood sheet and carefully cut it out to size using a jig-saw (a hand saw, table saw, or skill-saw would also work fine). After I had finished cutting it out I then made sure to sand all of the rough edges on the base and back board to make it more pet friendly.

Step 3: MAKING THE SUPPORT BLOCKS

After having cut out my plywood base and back board I was trying to find a way to securely attach the back board onto the base so that it was strong enough to take some beating and support the weight of a full soda bottle. To do this I simply marked out one line that went from the bottom end corner of the plank up to the top edge at a 45 degree angle and a second that ran directly down from the top edge to the bottom edge at a 90 degree angle. Next I used a clamp to securely lock the 4/2 plank down onto my cutting jig so that I could make accurate cuts along my markings (I would recommend using a cutting jig as humans have a tendency to generally suck at cutting straight lines with just a hand saw). Once I had made the two cuts I then had two small triangle shaped support blocks that I could use to secure the back board to the base at a perfect 90 degree angle.

Step 4: ATTACHING THE SUPPORT BLOCKS TO THE BASE

After I had found a way to securely attach my back board to my base at a 90 degree angle and had build the support blocks I then needed to decide where the back board would be attached. I wanted to have the back board attached as far to one end of the base as possible in order to leave plenty of space for the pet to stand on and be able to comfortably drink from the water bowl without any hassle. Firstly I roughly aligned the two support blocks about where I wanted them to be attached to the base. I then got the dimensions of my support blocks and after much measuring and marking I had drawn out exactly where I was going to attach them to the base. After that I marked out where I was going to drill guide holes through the plywood base and put markings on the bottom of the support blocks to match the ones that were on the base. I then used an electric hand drill to drill a set of guide holes through the plywood base and then drilled matching ones into the bottom of the support blocks. Lastly I held the support blocks in place while I secured them to the base using some wood screws.

Step 5: ATTACHING THE BACK BOARD TO THE BASE

To attach the back board to the base I simply held it in place up against the support blocks at a 90 degree angle and traced around them to give me a pretty good idea where I could drive the screw in. I then marked out and drilled guide holes horizontally through the back board and directly into the support blocks behind. After that I once again held the back board in place up against the support blocks at a 90 degree angle and drove wood screws into the guide holes tightly securing it to the two support blocks and to the base of the design. This proved to work great as it is very secure and will be able to stand up to a lot of beating.

Step 6: ATTACHING THE SODA BOTTLE TO THE BACK BOARD

Next what I did was measure and draw a line vertically down the center of the back board to help me align the soda bottle correctly in the middle of the board. After I had done that I was able to roughly align the soda bottle at the height in which I wanted it to be attached so that I could see where I had to drill holes through the back board for the hose clamp to travel through.To help you gauge the height that your soda bottle needs to be secured at and where you will need to drill the holes for the hose clamp to go through, simply fill up your bowl 3/4 full with water and place it at the base of the back board. Then put a mark on your soda bottle where the hose clamp will secure it to the back board. Now hold your soda bottle up side down against the back board and lower it down until the lid just touches the surface of the water then stop and make a mark on the back board as the same level as the mark you put on your soda bottle. This mark will be the height that you will drill the holes for the hose clamp to go through. Lastly, at the same height as the mark that you have just made on your back board, drill a hole approximately 3 centimeters from the center line on each side (refer to the photos if you are confused). Now you can feed the hose clamp through the two holes and secure your soda bottle firmly onto the back board.

Step 7: PAINT JOB

Painting you self refilling water bowl for your pets is obviously optional and completely dependent on your style so go crazy and create something awesome! I would love to see your awesome designs in the comments below!