Instruction: Answer the given question using the supporting document.

Input:
Question: How often do you have to add water?
Document: works excellent, love the ability to add as much water as I like,  has helped a great deal in sleeping, super satisfied
I was replacing the same brand that I purchased about 5 years ago, but it isn't the same. My original pillow was much thicker. This one is softer and has less filling, causing me to add more water. I have gone back to my old one.
After about 10 minutes trying to add the perfect amount of water (and remove air bubbles), I thought this would finally give me a great night's sleep, based on all the good reviews. Not only is it not that great of a pillow, but with the water it becomes so heavy, that it becomes really inconvenient if you move around alot at night.
I've had this pillow for about a year, and LOVE THIS PILLOW! My chiropractor charged a lot more for this same pillow, so I got mine through Amazon. It has relieved a lot of my morning neck pain and stiffness, and I highly recommend it. After you fill it to your comfort, you do need to occasionally adjust it (add a cup of water or so)  to it every now and then, as the foam settles down over time.
I've been having neck aches for months and this pillow was recommended by a  chiropractor for my daughter. Found it for less on Amazon and it didn't take long before I saw improvements. You alter how soft or hard you want it so it takes the guess work out of which pillow to buy. If it doesn't feel right you change the amount of water you add. Great for back or side sleepers. Highly recommend!
I have used these pillows for the past 10 years after being in a rear end collision. My chiro sold me the first one and I have replace several times. The pillow is so good I no longer need adjustments. The trick is to start with the lowest level of water in the instructions then give it a few nights before deciding to add more. Then if you do only add a little at a time and then give it another few nights.
I was having neck pain for the past few nights, because I couldn't sleep properly. The moment I got this pillow it went away. It's so easy to fall asleep in it, and yes Im a person with insomnia. But something about how well this conforms to you just makes you in the sleeping state. It was very easy to set up and add water. I don't ever here the water swish around while I try to move from my back to side.
So glad I did! I started out with the least amount of water to see how it did, and noticed some improvement the first couple of weeks. I like to sleep on my side and realized that I would need to add another quart of water to get the proper firmness for side sleeping. My neck has felt great ever since. Problem solved! I highly recommend this pillow for anyone with neck pain and am going to get another one later for hubby!
I bought a very expensive Sleep Number pillow because I suffered from morning neck pains and wanted to resolve it. I like firm pillows ( or so I thought ), so I got a firm neck pillow. It was a big improvement but I was still having neck pains every so often. A friend told me about water pillows, and saw how affordable they were here, so I decided to pick one up. This is personally my favorite pillow.
I was having neck pain and getting headaches often. I may have a little soreness from time to time now, but nothing a little stretching won't alleviate. I love that this pillow maintains its shape and you never have to fluff or readjust it. Even if you prefer a soft or medium pillow (like I do) I would recommend filling it more than suggested.
Answer: Once and done. Unless you want to add or remove water to change the firmness / support.