Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2020	Nov. 30, 2020	Mar. 31, 2020
Entity Registrant Name	OneWater Marine Inc.
Entity Central Index Key	0001772921
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Public Float			$ 53,880,098
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Address, State or Province	GA
Common Class A [Member]
Entity Common Stock, Shares Outstanding		10,779,119
Common Class B [Member]
Entity Common Stock, Shares Outstanding		4,196,179