Where is the shut off valve to drain the fresh water tank

no info generic answer ---owners manual ---manufacturer --rv dealer ---rv service center

You will have shut off valves or caps on three (3) drain points under the RV. One is to drain the hot water, one for the cold water lines and the other is to drain the fresh water tank. At least once a year, add 1/4 cup of bleach to the fresh water tank and fill it up with fresh water. Then turn on the water pump and run water through each faucet (kitchen/bathroom/shower) for 3-4 minutes. This will sanitize all the lines and outlet fixtures.

Look underneath the camper for a drain valve. Never seen a Jayco without a factory installed drain valve.

Disconnect clear water supply/hose. Turn on 12v pump. Turn on the sink faucets and open the grey water drain. Wait until the faucets start spitting water (you'll know).
Complete.
If you wish to split hairs yes there will be residual water left somewhat in the system but the tank will be emptied. Good luck and happy camping

Here are some troubleshooting steps you can try to resolve the problem:
1. Check the Water Pump:
- Make sure the water pump is turned on and functioning correctly. The water pump is responsible for drawing fresh water into the holding tank from an external source.
- Check for any visible signs of damage or blockages in the water pump system.
2. Verify the Tank Fill Valve Position:
- Ensure that the tank fill valve is in the correct position to allow water to flow into the holding tank. The valve may need to be switched from the city water connection to the tank fill position.
3. Inspect the Water Inlet:
- Check the water inlet connection where you fill the fresh water tank. Make sure there are no obstructions or kinks in the hose that could be preventing water from entering the tank.
- If there is a water filter in the system, check if it is clogged and needs to be replaced or cleaned.
4. Test the Gravity Fill System:
- If your RV has a gravity fill system for the fresh water tank, try filling the tank using this method. Pour water directly into the gravity fill port and monitor the tank level to see if the water is entering the tank.
5. Consult the RV Manual:
- Refer to the owner's manual of your Coachmen Elite RV for specific instructions on filling the fresh water tank and troubleshooting water system issues.
I good luck

The water tank drain should have a shut off valve to prevent water leak. I wouldn't cap it, you should want to drain water tank on occasion.

If it is a big valve it is your sewer tank drain valve. There is two valves. One is the Black water drain and the other is the gray water drain. the black water drain comes from the toilet holding tank, and the gray water valve drains the shower and sink holding tank.

Find where the fresh water tank fill is located. Directly below that under the coach you should see a single low point drain for the fresh water tank. It may have a cap on it but it may also have a valve at the location of the drain hose to the tank fitting.

There should be a fresh water fill on the outside of the coach. If not then there is a valve that would need to be turned that will allow water to be put into the fresh water tank. If that is the case then it will be a bit more difficult to put bleach into the fresh water tank but not impossible. There will be a pump that draws fresh water out of the tank. You can disconnect the input and output lines. Connect the input line which comes from the fresh water tank to the output side of the pump. Then using a flexible line with a 1/2" pipe thread fitting, connect that to the input side of the pump. Put the loose end of the flexible line into a gallon of bleach and turn the pump on. It will draw the bleach out of the container and pump it into the fresh water holding tank. Now return the plumbing of the pump back to the original configuration. Using the valve system complete filling the fresh water tank with fresh water and allow to sit for a couple of days. Then open the low point drain on the fresh water tank and completely drain. When the coach is not in use make sure the tank is completely drained. There is also a fresh water treatment that you can purchase at your local rv parts department.

There should be three low point drains located under the trailer. Two will be close, side by side, to one another. This is the low point for the entire plumbing system, both cold and hot. There will be another single low point drain which will be for the fresh water tank. The low point drains may only have a cap on them or may have a valve installed.