Probably a pretty standard size coming out of the sink, bring that attachment into the store to size it up, simple RV filter is all you need https://www.walmart.com/ip/Camco-TastePURE-RV-and-Marine-Water-Filter/29764358 I wouldn't even bother using the filter it came with and make sure to run the new filter into the sink first to get all the black carbon that comes out when first used. Get some H202 test strips and keep 50-100ppm H202 in the tank to help sanitize, shock occasionally with potassium peroxymonopersulfate https://www.amazon.com/Test-Strips-Peroxide-0-100ppm-PK/dp/B007IBHHLO https://www.spadepot.com/Oxy-Spa-Non-chlorine-MPS-Shock-One-Half-lbs-P77?zmam=55673001&zmas=1&zmac=1&zmap=CA1021&gclid=EAIaIQobChMIveP2vdWv3QIVBrXACh2sxgp_EAQYAiABEgL9Z_D_BwE Enjoy your new tent and message me if you need anything :)