Our Water Ridge dual toilet is making loud groaning sound each time we flush. Once water level fills, the noise stops. Anyone experience this and found fix?

A dual flush toilet is a fantastic option to save water and make your home more environmentally friendly. Giving you the option for a half flush or full flush at your discretion, you can lower your water consumption while still getting the job done. However, like all toilets, they can present problems that mean the toilet doesn't function as it should. One common problem in dual flush toilets is constantly running. You hear the tank constantly being filled, even when it should be finished and completely full. If your dual flush toilet is constantly running, first check for the top three problems that cause this trouble:
Flapper or Seal Trouble
The flapper or seal is often the culprit in constant running water in both normal and dual flush toilets. Over time, this rubber piece may become brittle or simply misaligned. To check it, turn off the water supply and flush the toilet to completely empty it of water. Remove any remaining water with a sponge or towel. Then, you'll need to remove the flush valve canister in order to access the seal. Once you've found the seal, check to see if there are any cracks in the seal. If there are, you'll need to replace it. Otherwise, check to see if it can be re-aligned to sit nicely in its place. Some homeowners find that applying a bit of Vaseline to the seal can renew it, making it supple and functional again for a while at least.
Debris
Sometimes the water supply isn't as clean as we think. Or, dust and dirt may be able to enter the toilet, causing the fill valve to malfunction. To check it, turn off the water supply and remove the lid from the fill valve. Then, look for any debris and remove it. You may also consider brushing out the valve with a small brush. Once you're certain it is clean, recap the valve and check if the problem has been solved.
Broken Zip Tie
The fill valve in most dual flush toilets has a zip tie to keep the base of the fill valve in place. If the fill valve isn't strongly secured, it can cause the toilet to run. Sometimes these ties wear out or break before the rest of the device does. You'll need to replace a broken zip tie with a new one if you find that it's broken. If possible, you can place two zip ties on the fill valve in order to assure that the base doesn't wobble, causing the leak. Many times these problems are easy for the average homeowner to check for and repair. In the case that you are not able to find a solution to your dual flush toilet's constant running, then you'll need to call in the help of a professional plumber. A high quality plumbing company will be able to help you troubleshoot your dual flush toilet troubles and make sure it's functioning properly again.

I have a glacier bay dual flush toilet. I have had it since 2009. When it started the hissing noise I tried diff things to fix it. New water valve, new washer from tank to bowel.
The food die in the tank showed water was leaking into the bowl. As a result the water would try to keep filling the take every time a little water escaped making it hiss. Sound familiar?
Finally I contacted someone on line home depot and the glacier bay manufacture was the main people. You need a silicone washer that goes in the main center piece mechanism that lets the water into your tank. You need to remove the center main piece in your tank. at the bottom inside the mechanism itself is a washer the size of a coffee mug top circle.
You can only see it if you take apart the two pieces. Once this goes inside your problem WILL BE SOLVED. The manufacture sent it to me for free. She knew right way. What causes the problem is cleaner tablets in the tank or bad water. So that's it folks

Hi, if you remove the cistern lid and flush the toilet, look at the float (back left) to see if this is rising freely when the water fills back up. Once the water has stopped filling, check the fill level lines on the large syphon in the middle of cistern. Your model of toilet has an eco flush which will be lowest line to save water, so not as much water will flush out. There is a long plastic screw on the float (back left) which you can turn to adjust the water level to the higher line on syphon (1.6 gallon flush) and turn it slowley till the water level reaches that mark. flush a couple of times to see it is filling back up to the set amount.

Make a note where your water level is then the tank is full. Replace the assembly that lets the water in with a Fluidmaster 400A fill valve, available at your local plumbing supply store.

I am not familiar with that model, but it sounds like your fill valve is leaking or the water level in the tank is too high. Take the toilet tank top off and flush the toilet. When the water gets full and you hear the water stop ( except for your leak) look at the flush valve. Is water running over the top of it and running into the hole in the middle? Then the float need adjustment.
If you are hearing you leak still, lift up on the float. Did it stop? if so the valve may need adjustment due to it not seating completely. You can probably find something online (youtube) easier than I can explain it.

May need to replace toilet flapper or entire flush valve. water is getting from the tank into the toilet which is causing this to happen.

Lift the tank lid off, place it somewhere safe for a moment, and look at what happens: If you're talking about jiggling the handle to get the tank to start to fill with water, then it sounds like the chain or rope is out of adjustment. It can't be TOO TIGHT or the water will leak past your flapper (will cause your dripping noise, tank water level will leak down, causing constant refills), and it cant be TOO LOOSE or the toilet won't flush correctly. Since you didn't mention trouble flushing the toilet, I think that it may be a little too TIGHT. When you jiggle the flush lever-it is supposed to pull a chain or cable to open the flapper at the bottom of the tank. Flush the tank and watch what happens-all the way through to refilling the tank with water and shutting off the water refill valve-Does the flapper get stuck on the chain or something? It is supposed to fall back down to allow the tank to refill after flushing out your toilet. Does the chain look very loose? The dripping sound you described indicates that the flapper is not sealing 100%. The flapper is very easy to replace, you just have to get the adjustment set for when you flush the toilet how sensitive you need it. You amy have to play with it a little bit before you get the adjustment correct.

Hope this helps!