We just used one type of apple out of convenience and it turned out beautifully. However, a great cider often has a mix of apples that are both tart and sweet varieties. You do NOT want to just add water as that will make the cider less sweet, but also thinner or more watery tasting. We’d suggest you top of the cider with pure apple juice. Just take a sample first and test it out to see if you like the taste. Also, if you happened to heat your cider to kill bacteria or put yeast in it, that also adds to the sweetness so you’d definitely need some tarter apples in the future. Just avoid too much tartness or it will be quite acidic.
We just used one type of apple out of convenience and it turned out beautifully. However, a great cider often has a mix of apples that are both tart and sweet varieties. You do NOT want to just add water as that will make the cider less sweet, but also thinner or more watery tasting. We’d suggest you top of the cider with pure apple juice. Just take a sample first and test it out to see if you like the taste. Also, if you happened to heat your cider to kill bacteria or put yeast in it, that also adds to the sweetness so you’d definitely need some tarter apples in the future. Just avoid too much tartness or it will be quite acidic.