The goalkeeper missed last weekend's 4-2 FA Cup victory over Bradford due to a one-match suspension, with 18-year-old Jonathan Bond coming in to make his full debut for the Hornets.
But Loach is expected to regain the gloves against the Royals at Vicarage Road, 5.20pm kick-off. Craig Forsyth replaced departed loan winger Michael Kightly to make his first start since early November and duly bagged a brace, meaning he is set to keep his place on the left of midfield.
Nyron Nosworthy has this week turned his loan stay into a permanent move and will continue in defence, but long-term absentees Martin Taylor (dislocated collarbone) and Stephen McGinn (knee) are not yet ready despite returning to training. Reading manager Brian McDermott is sweating over the fitness of a whole host of players.
McDermott could be without captain Jobi McAnuff (groin), midfielder Mikele Leigertwood (thigh) and striker Noel Hunt (ankle), all of whom are doubts for the weekend.
The same applies to defender Andy Griffin, who has missed the Royals' last two matches with an Achilles injury, while frontman Mathieu Manset has been ruled out of the visit to the Hornets with a knee problem.
Diminutive midfielder Jay Tabb, who was substituted with a minor knock during the 1-0 home defeat to Stevenage in the third round of the FA Cup last Saturday, should be fit to feature for McDermott while Jem Karacan is in line for a recall after being left out against Boro.
Winger Jimmy Kebe should be available to McDermott following a knee complaint but new signing Karl Sheppard has not played since December 15 and is not yet fully match-fit.
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