Some people change their bath water everyday while others change it every two or three days.
Some people use new bath water daily but other people use the same bath water for two or three days in a row.
質問を読んで「えっ！？」と驚いてしまいました笑
どちらも「お風呂の水を毎日替える人もいれば、２〜３日おきに替える人もいる。」という意味になります。
Some people change their bath water everyday while others change it every two or three days.
「お風呂の水」は bath water
change their bath water every two or three days で「お風呂の水を２〜３日おきに替える」
Some people use new bath water daily but other people use the same bath water for two or three days in a row.
use new bath water daily で「日毎に新しいお風呂の水を使う」
for two or three days in a row で「2~3日続けて」
ご参考になれば幸いです！
日本 
