I feel this should be correct, in English you could have a pool of any other liquid. Pool implies a body of water of various sizes, but not specifically for swimming.
It could be. Duo teaches three ways to ask, "Do you have ...?:
¿Tienes (tú) ...?
¿Tiene (usted) ...?
¿Tienen (ustedes) ...?
All three should be accepted.
Wouldn't using tienen make it plural? I thought the phrase said "do they have a pool" Is there a reason they use tienen instead of just tienes? Thanks in advance
ustedES is the plural of "you", like "you all". So, you are addressing the question to multiple people. In (Latin American) Spanish, the correct verb form for the plural "you" is the same as "they." (Spain Spanish has an informal "you all" which is "vosotros" (for -ar, -er, and -ir verbs the conjugations is -áis, -éis, and ís, respecectively, for the simple present.)
Is "¿Vosotros tienen una piscina?" correct or only "¿Vosotros tenéis una piscina?" can be used?
Yo tengo. Tú tienes. Usted tiene. Él tiene. Nosotros tenemos. Ustedes tienen. Ellos tienen. Here a native Spanish speaker