Water Plantain (Alisma plantago-aquatica) has a long history of use in traditional medicine systems, particularly in East Asia. In Traditional Chinese Medicine (TCM), it is known as "Ze Xie" and is commonly used as a diuretic herb, believed to "drain dampness" and support urinary health, including conditions such as urinary tract infections and kidney-related ailments. Historical herbal texts describe water plantain as beneficial for promoting urination and alleviating symptoms associated with urinary retention, edema, and infections affecting the kidneys and bladder.

However, scientific research specifically evaluating the efficacy of water plantain for treating kidney infections (pyelonephritis) is limited. Most modern studies focus on its diuretic and anti-inflammatory properties, with only a few in vitro or animal studies suggesting possible antimicrobial or nephroprotective effects. There are no high-quality clinical trials confirming its effectiveness for kidney infections in humans. As such, while its use is deeply rooted in tradition and it is included in several classical herbal formulas for urinary and kidney disorders, robust scientific validation is lacking.

In summary, water plantain's use for kidney infections is primarily supported by traditional practices rather than solid scientific evidence, and its efficacy for this specific condition should be considered unproven from a modern medical perspective.