G.A., Windham, N.H.

A. It should be safe because muriatic acid attacks lime (and will help dissolve that hardened mortar), and there is no lime in the plastic. The acid could etch any metal, say, where the plastic connects to copper or cast iron. Just be careful pouring the acid into the drain; keep it off the metal rim around the drain opening. And thinking about acid, it occurs to me that nonenzyme Drano, which is an acid, has been used for years without damage to pipes of any sort.

Dilute the acid half and half with water. Always pour acid into water. Pour the acid solution very carefully into the drain, making sure it does not splash. A funnel will accomplish this. Wear skin and eye protection when working with acid.

Q. I have stripped the paper off horsehair-plaster walls in my newly purchased condo. So far so good. But there's a lot of paste left. How best can I remove it? It is too soft to sand off, and while water softens the paste, it still is difficult to remove.

I'd also like to relocate the toilet drain so I can get the side of the toilet 3 or 4 inches closer to the wall. Is that possible or feasible?

A.C., Cambridge

A. That paste is a combination of paste and glue size, which was applied to the wall before the paper was hung. And you're right; water will soften it but it does resist removal, feeling very slippery when you try. So, make a super-strong solution of Spic and Span and water, which will tend to dissolve the paste and make it easier to scrape off. You may have to do it several times. And, at the beginning, if you soften the paste with water, you can scrape a lot of it off with a wide putty knife.

Even if you don't get it all off, you can leave some of it on to dry, and if it is smooth, you can paper right over it. If you plan to paint, you have to remove every trace of it. And that means washing and washing again.

As for relocating the toilet drain, it is possible but not feasible, because it would entail more work and plumbing than is worth the trouble and expense. I wouldn't bother.

Q. Water runs down my open outside cellar stairs and goes into a drain at the bottom of the steps, but often I have to clean out the debris that collects in the drain; if I don't, the drain floods. How can I keep the drain clear?

FLORA HAAS, Arlington

A. A stiff screen (hardware cloth should do; it is half-inch steel mesh) directly under the drain cover will stop the debris and make it easier to remove.

A more permanent fix (and one that would prevent water going into the drain, is to build a bulkhead roof over the open steps. If that is not practical, you can build a shed over the opening, with a roof and side walls.

Q. I have been getting as much as 5 inches of water in the basement of my one-year-old house. The water is coming from the sump, which simply overflows. A man suggested a French drain, which would cost $3,000. Any different ideas?

DEBORAH HAMBLY, Middleborough

A. If the house is less than a year old, or the problem occurred before a year was up, the builder should put the French drain in for free; he should have done it in the first place. If you can get him to do that, fine, but being more realistic, your first step is to install a pump in that sump, which would pump away the water that fills the sump before it overflows.

However, that much water might be too much for the pump, so then your next step is a French drain. Cost is in the ball park, and the drain may allow the pump to keep ahead of the rising water.

Q. I replaced a step in my yard with brick and bluestone, but now rainwater builds up on the concrete patio against the step. It is not too bad in summer, but I'm afraid it will create an ice rink in winter, where I don't want it. Can I drill holes in the concrete for drainage? The old wood step I replaced allowed water to drain away through the open riser.

H.G., Cambridge

A. While you asked the question, the Handyman came up with all kinds of ways that would allow drainage of that flooding water. All of his ideas, such as regrading the patio, were expensive. But he did not think of drilling holes in the concrete. It's a good idea. Rent an impact drill (a drill, basically, that acts as jack hammer as well as a drill). Make half-inch diameter holes the full thickness of the patio, 3 or 4 inches apart.

Avoid drilling the holes with a regular drill; you'd be working for weeks and it simply will not work. You can fill the holes with sand if you like. Water will drain through the sand.

Q. I like your idea of putting a concrete apron around the house to allow dripping water to hit the apron rather than dirt. What about just using crushed stone around the perimeter; wouldn't that work just as well, sort of cushioning the dripping water? But for concrete, what formula can I use? How about Sakrete by the bag?

DORIS ROBERTS, Dorchester

A. The apron or the crushed stone ``trench'' is used mainly on houses without gutters, to prevent dripping water from splashing onto dirt and staining the siding. The trench of crushed stone is easy to make and will look good for years. One problem with a trench is that it might allow dripping water to run down the foundation and cause leaks. If that doesn't happen, the crushed stone trench is the best way to go. It can be just a few inches deep.

The concrete apron will be neater looking and not only prevent staining of the siding from splashing water but also, with any luck, guide the water away from the house to prevent it from running down the foundation.

A typical apron is 6 or 8 inches deep, with a few inches above ground, 18 inches wide, and sloped ever so slightly for runoff. The width of the apron depends on how wide your roof overhang is. If the roof overhang is, say, 24 inches, then you want to make the apron at least 30 inches.

Sakrete is OK to use for small projects, but a bag, even a 90-pound bag, will not go very far for an apron. So, instead, I suggest renting an electric concrete mixer from a rental store. It allows concrete to be made in medium-size batches and will provide all the mixing muscle needed.

As for a formula for mixing your own concrete, the classic 1:2:3 formula will do well: 1 part Portland cement, 2 parts sand, and 3 parts crushed stone. Add enough water to make a crumbly, not a soupy, mix.

Q. I have a sump hole in my basement that acts as a drain for the condensing water from my air conditioning system. It is 3 inches wide and 18 inches deep, and in heavy rains the hole fills and water backs up to flood the floor. How can I prevent that?

JUDY AND DAVID SCHURGIN, Malden

A. The flooding is caused by the level of water underground (ground water or water table, take your pick for a name), which rose during heavy rains, filled the hole from below, and flooded the floor.

The problem, I think, is that the sump hole (that's a redundancy; a sump is a hole) is way too small for the amount of water it gets. Make the sump bigger: 18 inches square and 24 inches deep. Add crushed stone to a depth of 6 inches. This bigger hole may handle the ground water plus the condensate from the A/C. If not, install a pump, which will pump the water automatically away from the house before it floods the floor.

Q. The set-tubs in my basement have small leaks, at the bottom of the sinks where they drain out. How can I fix them myself?

ELLIE CRONIN, Melrose

A. Since the leaks are at the drains, dismantle the drains and drain covers and install plumber's putty in the openings before putting them back. And don't put them back too tightly.

Q. Last March, I had water in my cellar for the first time in 37 years. It was 2 inches then, and even more again in May. I plan to have a sump and pump installed. Is that good?

M.M., Waltham, Mass.

A. It certainly is good, and it might solve your problem. The reason you got flooding is that the spring brought above-normal rainfall, which raised the water table, the level of water under ground. This level got high enough to push against the concrete floor of the basement, but did not go through the floor but came in through the joint between the floor and foundation.

What the sump (hole in the floor) does is allow the water to fill that hole before it forces its way onto the floor. The pump automatically pumps it away.

A sump and pump will work under many conditions. For a higher water table and more severe flooding, a French drain may be needed; this is a perforated pipe under the cellar floor all the way around the inside perimeter of the foundation. This pipe picks up water under the floor and delivers it to the sump and pump before it floods the floor. As you can guess, it is expensive. If the sump and pump alone do the job, then you don't need the French drain.