I’ve been brewing at home now for about three years and while I’ve brewed a couple of ‘pseudolagers’, with uneven results, I haven’t brewed a proper lager at home yet. Lager is surprisingly hard to brew well on a domestic scale. This is true for several reasons. The first is that lager is often brewed with lager yeast. I say ‘often’ and not ‘always’ because there is a difference between ‘lager’ the style designation and ‘lager’ the yeast designation. The lager style, of course, is simply a light coloured, lightly hopped, dry-tasting, well-carbonated beer. It can have hints of cooked vegetable (tinned tomato and sweet corn) in the taste from above the taste threshold levels of dimethyl sulphide. It shouldn’t be fruity or estery tasting. A lager yeast is, as it happens, the yeast that is characteristically used to make a lager style beer. Lager yeast is hard to manage at home because it wants a cool fermentation temperature of about twelve degrees celsius (sometimes commercial breweries go up to 15C to speed up the fermentation, but the danger is that at this comparatively hot temperature for a lager yeast, the yeast will produce a very estery, fruity tasting beer). Unless you have a cellar, its hard to find somewhere in the house that is a steady 12C degrees. Some homebrewers put their fermenter in a fridge and modify the thermostat to hold 12C.
Even if I solved the problem of the fermentation temperature, there would be another hurdle to overcome. Lager is not supposed to be estery or fruity. Esters like ethyl acetate and isoamyl acetate are produced as metabolic byproducts during fermentation. They taste sweet and fruity. Certain fermentation conditions encourage ester production. In particular, low wort oxygen levels and low fermentation vessel pressure (hydrostatic head) encourage ester production. A commercial brewery uses sealed cylindro-conical fermentation vessels, which are tall and narrow and hence subject the yeast to higher pressures.. They also dissolve pure oxygen into the wort to achieve level of 15 parts per million O2. The most O2 you can dissolve into wort by aeration is 8 parts per million, so to brew a lager at home you’d need a way to inject that oxygen. Some homebrewers use aquarium equipment.
The long and the short of it is that any homebrewed lager runs the risk of being too sweet and fruity, because the operating temperature of the yeast, the shape of the fermentation vessels and the amount of oxygen in the wort are all conducive to high levels of esters in the beer. So you’re not going to get that classic dry lager taste.