Yup.
2 Tablespoons of fresh lemon juice is fine - I recommend using fresh lemons as there are no preservatives injected into those little yellow gems! Those little plastic lemon-shaped squeezey bottles have additives.
Minute Maid™ packages 100% frozen lemon juice. It is sometimes hard to find; not all grocers carry it. It comes in a yellow plastic squeeze bottle tucked inside a yellow cardboard box with black lettering. It's about 3" x 7" x 1" and is usually located in the freezer case (Rarely at eye level) near the frozen daiquiri mixes or limeade. Sometimes it is near the frozen fish in the freezer case.
For people having a hard time getting their water down, sometimes having a cup of hot water with a squeeze of lemon juice or a glass of chilled water with a drizzle of lemon juice makes it easier drink the water. Made like hot tea with a packet of Splenda™ added, it fills up the tummy.
It is also good drizzled on steamed veggies, thinly sliced and baked with chicken or fish.
Since lemons do have carbohydrates, we limit the serving size to 2 Tablespoons a day.