George Quantrell picked out the top corner to give the hosts a deserved lead but United soon equalised through full-back Callum Cocks.
We fell behind for the second time in the match six minutes later when Joe Marsden and Ross Crane scored in rapid succession to restore their lead in the buildup to the break.
In a uphill second-half battle for Long Eaton, Crane scored late in the day to secure his brace and wrap up the host's midweek win.
Brad Munn made two changes to the starting lineup that faced Redditch United at the weekend. Reece Bertram made his return from suspension to replace Luke Martin at centre-half, while James Spruce started in attack.
Leiston started on the front foot but three almost successive corner kick routines resulted in no clear cut chances for the hosts.
Jamar Loza had a chance from inside the box but from a tight angle failed to hit the target.
Jack Manly was a constant threat down the left and on the 20th minute saw his effort blocked before Crane’s rebound was blasted straight into the gloves of Ross Durrant.
Just past the half-hour mark Quantrell curled the ball into the top corner to put the hosts in front. Then, less than a minute later, Durrant was called into action again and denied Manly from close-range.
Against the run of play Long Eaton found a reply. Callum Cocks arrived at the back post and equalised with a poacher’s finish after Sam Donkin parried Cieron Keane’s cross into the path of the full-back.
Moments later George Atwal almost found the goal to put The Blues ahead but this time Donkin pushed the effort behind.
However, the hosts were soon back in the ascendancy and restored their advantage, Marsden heading the ball home from Quantrell’s cross. Just before the break Crane fired in Leiston’s third to give the hosts a two goal cushion after 45 minutes played.
After the restart Loza showcased his ability on the ball with a great solo run but Durrant made a diving save to stop the winger’s low strike.
Durrant was quick off his line to deny Crane a second, this time the forward’s lobbed shot was stopped by the forearm of the Long Eaton United number one.
Leiston continued to be a threat in the wide areas and Quantrell had a chance to further extend the lead but headed the ball over the crossbar from close-range.
Andy Kanga had an opportunity to reduce the deficit from the edge of the area but his half volley was parried wide by Donkin.
Loza almost had his perseverance rewarded with a goal but his attempt late on in the match struck the post and fell to Crane who slotted away the rebound to put the game to bed with his second of the evening and the hosts fourth.