In Japan they don't seem to have a problem to put a sink (for handwashing) that drains to the reserve tank: https://imgcp.aacdn.jp/img-a/1200/auto/global-aaj-f

In Japan they don't seem to have a problem to put a sink (for handwashing) that drains to the reserve tank: https://imgcp.aacdn.jp/img-a/1200/auto/global-aaj-front/article/2015/11/5638b96863c22_5638b70c16ca4_1863994658.jpg https://imgcp.aacdn.jp/img-a/1200/auto/global-aaj-front/arti...